2021 Serbia Open – Men's singles

{{Infobox tennis tournament event|2021|Serbia Open|

| defchamp =

| champ ={{flagicon|ITA}} Matteo Berrettini

| runner ={{flagicon|RUS}} Aslan Karatsev

| score =6–1, 3–6, 7–6(7–0)

| edition = 5th

| before_year = 2012

| after_name = Serbia Open – Singles

|draw=28 (4 Q/ 3 WC)|seeds=8}}

{{main article|2021 Serbia Open}}

Matteo Berrettini defeated Aslan Karatsev in the final, 6–1, 3–6, 7–6(7–0) to win the men's singles tennis title at the 2021 Serbia Open.{{cite web| title=Berrettini Battles Past Karatsev For Belgrade Title | url=https://www.atptour.com/en/news/berrettini-karatsev-belgrade-2021-sunday-final | website = atpworldtour.com | publisher = ATP | date = 25 April 2021 | accessdate = 29 April 2021}}

Andreas Seppi was the reigning champion from when the event was last held in 2012, but he decided not to participate this year.{{cite web|url=https://www.atptour.com/en/news/budapest-tournament-relocates-to-belgrade-2021|title=ATP Tour To Return To Belgrade In 2021, Following Budapest Relocation|website=ATP Tour|date=20 January 2021}}

Seeds

The top four seeds received a bye into the second round.

{{columns-list|colwidth=30em|

  1. {{flagicon|SRB}} Novak Djokovic (semifinals)
  2. {{flagicon|ITA}} Matteo Berrettini (champion)
  3. {{flagicon|RUS}} Aslan Karatsev (final)
  4. {{flagicon|SRB}} Dušan Lajović (second round)
  5. {{flagicon|SRB}} Filip Krajinović (quarterfinals)
  6. {{flagicon|HUN}} Márton Fucsovics (withdrew)
  7. {{flagicon|AUS}} John Millman (second round)
  8. {{flagicon|SRB}} Miomir Kecmanović (quarterfinals)
  9. {{flagicon|SRB}} Laslo Đere (first round)

}}

Draw

{{Draw key}}

=Finals=

{{4TeamBracket-Tennis3-v2

| RD1=Semifinals

| RD2=Final

| team-width=175

| RD1-seed1=1

| RD1-team1={{flagicon|SRB}} Novak Djokovic

| RD1-score1-1=5

| RD1-score1-2=6

| RD1-score1-3=4

| RD1-seed2=3

| RD1-team2={{flagicon|RUS}} Aslan Karatsev

| RD1-score2-1=7

| RD1-score2-2=4

| RD1-score2-3=6

| RD1-seed3=LL

| RD1-team3={{flagicon|JPN}} Taro Daniel

| RD1-score3-1=1

| RD1-score3-2=77

| RD1-score3-3=0

| RD1-seed4=2

| RD1-team4={{flagicon|ITA}} Matteo Berrettini

| RD1-score4-1=6

| RD1-score4-2=65

| RD1-score4-3=6

| RD2-seed1=3

| RD2-team1={{flagicon|RUS}} Aslan Karatsev

| RD2-score1-1=1

| RD2-score1-2=6

| RD2-score1-3=60

| RD2-seed2=2

| RD2-team2={{flagicon|ITA}} Matteo Berrettini

| RD2-score2-1=6

| RD2-score2-2=3

| RD2-score2-3=77

}}

=Top half=

{{16TeamBracket-Compact-Tennis3-Byes

| RD1=First round

| RD2=Second round

| RD3=Quarterfinals

| RD4=Semifinals

| RD1-seed03= 

| RD1-team03={{flagicon|KOR}} S-w Kwon

| RD1-score03-1=6

| RD1-score03-2=7

| RD1-score03-3=

| RD1-seed04=LL

| RD1-team04={{flagicon|ESP}} R Carballés Baena

| RD1-score04-1=3

| RD1-score04-2=5

| RD1-score04-3=

| RD1-seed05=Q

| RD1-team05={{flagicon|FRA}} A Rinderknech

| RD1-score05-1=6

| RD1-score05-2=7

| RD1-score05-3=

| RD1-seed06= 

| RD1-team06={{flagicon|ARG}} JI Londero

| RD1-score06-1=1

| RD1-score06-2=5

| RD1-score06-3=

| RD1-seed07=Q

| RD1-team07={{flagicon|ARG}} F Bagnis

| RD1-score07-1=65

| RD1-score07-2=64

| RD1-score07-3=

| RD1-seed08=8

| RD1-team08={{flagicon|SRB}} M Kecmanović

| RD1-score08-1=77

| RD1-score08-2=77

| RD1-score08-3=

| RD1-seed11= 

| RD1-team11={{flagicon|USA}} S Korda

| RD1-score11-1=5

| RD1-score11-2=6

| RD1-score11-3=65

| RD1-seed12= 

| RD1-team12={{flagicon|SLO}} A Bedene

| RD1-score12-1=7

| RD1-score12-2=1

| RD1-score12-3=77

| RD1-seed13=Q

| RD1-team13={{flagicon|ARG}} F Cerúndolo

| RD1-score13-1=6

| RD1-score13-2=65

| RD1-score13-3=66

| RD1-seed14= 

| RD1-team14={{flagicon|AUS}} A Popyrin

| RD1-score14-1=4

| RD1-score14-2=77

| RD1-score14-3=78

| RD1-seed15=Q

| RD1-team15={{flagicon|ITA}} G Mager

| RD1-score15-1=6

| RD1-score15-2=6

| RD1-score15-3=

| RD1-seed16=9

| RD1-team16={{flagicon|SRB}} L Đere

| RD1-score16-1=4

| RD1-score16-2=3

| RD1-score16-3=

| RD2-seed01=1

| RD2-team01={{flagicon|SRB}} N Djokovic

| RD2-score01-1=6

| RD2-score01-2=6

| RD2-score01-3=

| RD2-seed02=

| RD2-team02={{flagicon|KOR}} S-w Kwon

| RD2-score02-1=1

| RD2-score02-2=3

| RD2-score02-3=

| RD2-seed03=Q

| RD2-team03={{flagicon|FRA}} A Rinderknech

| RD2-score03-1=3

| RD2-score03-2=6

| RD2-score03-3=3

| RD2-seed04=8

| RD2-team04={{flagicon|SRB}} M Kecmanović

| RD2-score04-1=6

| RD2-score04-2=3

| RD2-score04-3=6

| RD2-seed05=3

| RD2-team05={{flagicon|RUS}} A Karatsev

| RD2-score05-1=6

| RD2-score05-2=4

| RD2-score05-3=77

| RD2-seed06=

| RD2-team06={{flagicon|SLO}} A Bedene

| RD2-score06-1=3

| RD2-score06-2=6

| RD2-score06-3=65

| RD2-seed07=

| RD2-team07={{flagicon|AUS}} A Popyrin

| RD2-score07-1=5

| RD2-score07-2=2

| RD2-score07-3=

| RD2-seed08=Q

| RD2-team08={{flagicon|ITA}} G Mager

| RD2-score08-1=7

| RD2-score08-2=6

| RD2-score08-3=

| RD3-seed01=1

| RD3-team01={{flagicon|SRB}} N Djokovic

| RD3-score01-1=6

| RD3-score01-2=6

| RD3-score01-3=

| RD3-seed02=8

| RD3-team02={{flagicon|SRB}} M Kecmanović

| RD3-score02-1=1

| RD3-score02-2=3

| RD3-score02-3=

| RD3-seed03=3

| RD3-team03={{flagicon|RUS}} A Karatsev

| RD3-score03-1=6

| RD3-score03-2=6

| RD3-score03-3=

| RD3-seed04=Q

| RD3-team04={{flagicon|ITA}} G Mager

| RD3-score04-1=3

| RD3-score04-2=4

| RD3-score04-3=

| RD4-seed01=1

| RD4-team01={{flagicon|SRB}} N Djokovic

| RD4-score01-1=5

| RD4-score01-2=6

| RD4-score01-3=4

| RD4-seed02=3

| RD4-team02={{flagicon|RUS}} A Karatsev

| RD4-score02-1=7

| RD4-score02-2=4

| RD4-score02-3=6

}}

=Bottom half=

{{16TeamBracket-Compact-Tennis3-Byes

| RD1=First round

| RD2=Second round

| RD3=Quarterfinals

| RD4=Semifinals

| RD1-seed01=7

| RD1-team01={{flagicon|AUS}} J Millman

| RD1-score01-1=7

| RD1-score01-2=6

| RD1-score01-3=

| RD1-seed02=WC

| RD1-team02={{flagicon|SRB}} D Petrović

| RD1-score02-1=5

| RD1-score02-2=4

| RD1-score02-3=

| RD1-seed03=LL

| RD1-team03={{flagicon|POR}} J Sousa

| RD1-score03-1=5

| RD1-score03-2=3

| RD1-score03-3=

| RD1-seed04=LL

| RD1-team04={{flagicon|JPN}} T Daniel

| RD1-score04-1=7

| RD1-score04-2=6

| RD1-score04-3=

| RD1-seed05= 

| RD1-team05={{flagicon|LTU}} R Berankis

| RD1-score05-1=4

| RD1-score05-2=6

| RD1-score05-3=1

| RD1-seed06= 

| RD1-team06={{flagicon|ARG}} F Delbonis

| RD1-score06-1=6

| RD1-score06-2=3

| RD1-score06-3=6

| RD1-seed09=5

| RD1-team09={{flagicon|SRB}} F Krajinović

| RD1-score09-1=7

| RD1-score09-2=5

| RD1-score09-3=6

| RD1-seed10= 

| RD1-team10={{flagicon|ITA}} S Travaglia

| RD1-score10-1=5

| RD1-score10-2=7

| RD1-score10-3=3

| RD1-seed11=WC

| RD1-team11={{flagicon|SRB}} N Milojević

| RD1-score11-1=6

| RD1-score11-2=6

| RD1-score11-3=

| RD1-seed12= 

| RD1-team12={{flagicon|ARG}} F Coria

| RD1-score12-1=4

| RD1-score12-2=0

| RD1-score12-3=

| RD1-seed13=WC

| RD1-team13={{flagicon|SRB}} V Troicki

| RD1-score13-1=1

| RD1-score13-2=4

| RD1-score13-3=

| RD1-seed14= 

| RD1-team14={{flagicon|ITA}} M Cecchinato

| RD1-score14-1=6

| RD1-score14-2=6

| RD1-score14-3=

| RD2-seed01=7

| RD2-team01={{flagicon|AUS}} J Millman

| RD2-score01-1=6

| RD2-score01-2=2

| RD2-score01-3=3

| RD2-seed02=LL

| RD2-team02={{flagicon|JPN}} T Daniel

| RD2-score02-1=3

| RD2-score02-2=6

| RD2-score02-3=6

| RD2-seed03=

| RD2-team03={{flagicon|ARG}} F Delbonis

| RD2-score03-1=6

| RD2-score03-2=2

| RD2-score03-3=6

| RD2-seed04=4

| RD2-team04={{flagicon|SRB}} D Lajović

| RD2-score04-1=3

| RD2-score04-2=6

| RD2-score04-3=4

| RD2-seed05=5

| RD2-team05={{flagicon|SRB}} F Krajinović

| RD2-score05-1=6

| RD2-score05-2=6

| RD2-score05-3=

| RD2-seed06=WC

| RD2-team06={{flagicon|SRB}} N Milojević

| RD2-score06-1=1

| RD2-score06-2=1

| RD2-score06-3=

| RD2-seed07=

| RD2-team07={{flagicon|ITA}} M Cecchinato

| RD2-score07-1=4

| RD2-score07-2=3

| RD2-score07-3=

| RD2-seed08=2

| RD2-team08={{flagicon|ITA}} M Berrettini

| RD2-score08-1=6

| RD2-score08-2=6

| RD2-score08-3=

| RD3-seed01=LL

| RD3-team01={{flagicon|JPN}} T Daniel

| RD3-score01-1=4

| RD3-score01-2=6

| RD3-score01-3=7

| RD3-seed02=

| RD3-team02={{flagicon|ARG}} F Delbonis

| RD3-score02-1=6

| RD3-score02-2=1

| RD3-score02-3=5

| RD3-seed03=5

| RD3-team03={{flagicon|SRB}} F Krajinović

| RD3-score03-1=4

| RD3-score03-2=4

| RD3-score03-3=

| RD3-seed04=2

| RD3-team04={{flagicon|ITA}} M Berrettini

| RD3-score04-1=6

| RD3-score04-2=6

| RD3-score04-3=

| RD4-seed01=LL

| RD4-team01={{flagicon|JPN}} T Daniel

| RD4-score01-1=1

| RD4-score01-2=77

| RD4-score01-3=0

| RD4-seed02=2

| RD4-team02={{flagicon|ITA}} M Berrettini

| RD4-score02-1=6

| RD4-score02-2=65

| RD4-score02-3=6

}}

Qualifying

=Seeds=

{{columns-list|colwidth=30em|

  1. {{flagicon|ITA}} Gianluca Mager (qualified)
  2. {{flagicon|ARG}} Facundo Bagnis (qualified)
  3. {{flagicon|ESP}} Roberto Carballés Baena (qualifying competition, lucky loser)
  4. {{flagicon|POR}} João Sousa (qualifying competition, lucky loser)
  5. {{flagicon|JPN}} Yūichi Sugita (first round)
  6. {{flagicon|COL}} Daniel Elahi Galán (first round)
  7. {{flagicon|ARG}} Francisco Cerúndolo (qualified)
  8. {{flagicon|JPN}} Taro Daniel (qualifying competition, lucky loser)

}}

=Qualifiers=

{{columns-list|colwidth=30em|

  1. {{flagicon|ITA}} Gianluca Mager
  2. {{flagicon|ARG}} Facundo Bagnis
  3. {{flagicon|ARG}} Francisco Cerúndolo
  4. {{flagicon|FRA}} Arthur Rinderknech

}}

=Lucky losers=

{{columns-list|colwidth=30em|

  1. {{flagicon|ESP}} Roberto Carballés Baena
  2. {{flagicon|POR}} João Sousa
  3. {{flagicon|JPN}} Taro Daniel

}}

=Qualifying draw=

==First qualifier==

{{4TeamBracket-Tennis3-v2

| RD1=First round

| RD2=Qualifying competition

| team-width=175

| RD1-seed1=1

| RD1-team1={{flagicon|ITA}} Gianluca Mager

| RD1-score1-1=4

| RD1-score1-2=77

| RD1-score1-3=6

| RD1-seed2= 

| RD1-team2={{flagicon|FRA}} Benjamin Bonzi

| RD1-score2-1=6

| RD1-score2-2=61

| RD1-score2-3=3

| RD1-seed3=WC

| RD1-team3={{flagicon|SRB}} Marko Miladinović

| RD1-score3-1=1

| RD1-score3-2=2

| RD1-score3-3=

| RD1-seed4=8

| RD1-team4={{flagicon|JPN}} Taro Daniel

| RD1-score4-1=6

| RD1-score4-2=6

| RD1-score4-3=

| RD2-seed1=1

| RD2-team1={{flagicon|ITA}} Gianluca Mager

| RD2-score1-1=6

| RD2-score1-2=4

| RD2-score1-3=6

| RD2-seed2=8

| RD2-team2={{flagicon|JPN}} Taro Daniel

| RD2-score2-1=1

| RD2-score2-2=6

| RD2-score2-3=4

}}

==Second qualifier==

{{4TeamBracket-Tennis3-v2

| RD1=First round

| RD2=Qualifying competition

| team-width=175

| RD1-seed1=2

| RD1-team1={{flagicon|ARG}} Facundo Bagnis

| RD1-score1-1=6

| RD1-score1-2=6

| RD1-score1-3=

| RD1-seed2= 

| RD1-team2={{flagicon|RUS}} Evgeny Donskoy

| RD1-score2-1=3

| RD1-score2-2=2

| RD1-score2-3=

| RD1-seed3=WC

| RD1-team3={{flagicon|SRB}} Hamad Međedović

| RD1-score3-1=77

| RD1-score3-2=77

| RD1-score3-3=

| RD1-seed4=6

| RD1-team4={{flagicon|COL}} Daniel Elahi Galán

| RD1-score4-1=64

| RD1-score4-2=65

| RD1-score4-3=

| RD2-seed1=2

| RD2-team1={{flagicon|ARG}} Facundo Bagnis

| RD2-score1-1=6

| RD2-score1-2=6

| RD2-score1-3=

| RD2-seed2=WC

| RD2-team2={{flagicon|SRB}} Hamad Međedović

| RD2-score2-1=4

| RD2-score2-2=2

| RD2-score2-3=

}}

==Third qualifier==

{{4TeamBracket-Tennis3-v2

| RD1=First round

| RD2=Qualifying competition

| team-width=175

| RD1-seed1=3

| RD1-team1={{flagicon|ESP}} Roberto Carballés Baena

| RD1-score1-1=77

| RD1-score1-2=2

| RD1-score1-3=0

| RD1-seed2= 

| RD1-team2={{flagicon|BIH}} Damir Džumhur

| RD1-score2-1=62

| RD1-score2-2=6

| RD1-score2-3=0r

| RD1-seed3= 

| RD1-team3={{flagicon|SVK}} Jozef Kovalík

| RD1-score3-1=5

| RD1-score3-2=4

| RD1-score3-3=

| RD1-seed4=7

| RD1-team4={{flagicon|ARG}} Francisco Cerúndolo

| RD1-score4-1=7

| RD1-score4-2=6

| RD1-score4-3=

| RD2-seed1=3

| RD2-team1={{flagicon|ESP}} Roberto Carballés Baena

| RD2-score1-1=66

| RD2-score1-2=4

| RD2-score1-3=

| RD2-seed2=7

| RD2-team2={{flagicon|ARG}} Francisco Cerúndolo

| RD2-score2-1=78

| RD2-score2-2=6

| RD2-score2-3=

}}

==Fourth qualifier==

{{4TeamBracket-Tennis3-v2

| RD1=First round

| RD2=Qualifying competition

| team-width=175

| RD1-seed1=4

| RD1-team1={{flagicon|POR}} João Sousa

| RD1-score1-1=6

| RD1-score1-2=6

| RD1-score1-3=

| RD1-seed2= 

| RD1-team2={{flagicon|USA}} Brandon Nakashima

| RD1-score2-1=4

| RD1-score2-2=2

| RD1-score2-3=

| RD1-seed3= 

| RD1-team3={{flagicon|FRA}} Arthur Rinderknech

| RD1-score3-1=6

| RD1-score3-2=6

| RD1-score3-3=

| RD1-seed4=5

| RD1-team4={{flagicon|JPN}} Yūichi Sugita

| RD1-score4-1=1

| RD1-score4-2=2

| RD1-score4-3=

| RD2-seed1=4

| RD2-team1={{flagicon|POR}} João Sousa

| RD2-score1-1=5

| RD2-score1-2=4

| RD2-score1-3=

| RD2-seed2= 

| RD2-team2={{flagicon|FRA}} Arthur Rinderknech

| RD2-score2-1=7

| RD2-score2-2=6

| RD2-score2-3=

}}

References

{{reflist}}