The 2021 Serbia Open was a tennis tournament played on outdoor clay courts. It was the 5th and 1st edition of the event for male and female professional tennis players, respectively. It was part of the 2021 ATP Tour and the 2021 WTA Tour and took place in Belgrade, Serbia; in mid-April for men and mid-May for women.^[1][2] A second ATP tournament, called the Belgrade Open, was played in men's singles the week before the French Open.

• Matteo Berrettini def. Aslan Karatsev, 6–1, 3–6, 7–6^(7–0)

• Paula Badosa def. Ana Konjuh 6–2, 2–0, ret.

• Ivan Sabanov / Matej Sabanov def. Ariel Behar / Gonzalo Escobar, 6–3, 7–6^(7–5)

• Aleksandra Krunić / Nina Stojanović def. Greet Minnen / Alison Van Uytvanck 6–0, 6–2

_{*per team}

Country	Player	Rank1	Seed
SRB	Novak Djokovic	1	1
ITA	Matteo Berrettini	10	2
RUS	Aslan Karatsev	29	3
SRB	Dušan Lajović	31	4
SRB	Filip Krajinović	37	5
HUN	Márton Fucsovics	40	6
AUS	John Millman	44	7
SRB	Miomir Kecmanović	47	8
SRB	Laslo Đere	49	9

• ¹ Rankings are as of 12 April 2021

The following players received wildcards into the main draw:

• Nikola Milojević
• Danilo Petrović
• Viktor Troicki

The following players received entry from the qualifying draw:

• Facundo Bagnis
• Francisco Cerúndolo
• Gianluca Mager
• Arthur Rinderknech

The following players received entry as lucky losers:

• Roberto Carballés Baena
• Taro Daniel
• João Sousa

Before the tournament

• Borna Ćorić → replaced by Federico Delbonis
• Pablo Cuevas → replaced by João Sousa
• Márton Fucsovics → replaced by Roberto Carballés Baena
• Gaël Monfils → replaced by Federico Coria
• Yoshihito Nishioka → replaced by Kwon Soon-woo
• Emil Ruusuvuori → replaced by Taro Daniel
• Dominic Thiem → replaced by Juan Ignacio Londero
• Fernando Verdasco → replaced by Alexei Popyrin
• Jiří Veselý → replaced by Marco Cecchinato
• Stan Wawrinka → replaced by Ričardas Berankis

Country	Player	Country	Player	Rank1	Seed
CRO	Nikola Mektić	CRO	Mate Pavić	5	1
USA	Austin Krajicek	AUT	Oliver Marach	71	2
RSA	Raven Klaasen	JPN	Ben McLachlan	71	3
ESA	Marcelo Arévalo	NED	Matwé Middelkoop	93	4

• Rankings are as of 12 April 2021

The following pairs received wildcards into the doubles main draw:

• Miomir Kecmanović / Dušan Lajović
• Ivan Sabanov / Matej Sabanov

The following pair received entry as an alternate:

• Artem Sitak / Stefano Travaglia

Before the tournament

• Nikola Mektić / Mate Pavić → Artem Sitak / Stefano Travaglia
• Hugo Nys / Tim Pütz → Matteo Berrettini / Andrea Vavassori

• Rohan Bopanna / Pablo Cuevas

Country	Player	Rank1	Seed
RUS	Anastasia Pavlyuchenkova	30	1
KAZ	Yulia Putintseva	34	2
CHN	Zhang Shuai	41	3
ESP	Paula Badosa	42	4
ARG	Nadia Podoroska	44	5
FRA	Kristina Mladenovic	53	6
SWE	Rebecca Peterson	61	7
MNE	Danka Kovinić	62	8

• ¹ Rankings are as of 10 May 2021

The following players received wildcards into the main draw:

• Olga Danilović
• Ivana Jorović
• Lola Radivojević

The following players received entry using a protected ranking:

• Mihaela Buzărnescu
• Andrea Petkovic

The following players received entry from the qualifying draw:

• Cristina Bucșa
• Réka Luca Jani
• Ana Konjuh
• Camila Osorio
• Kamilla Rakhimova
• Wang Xiyu

The following player received entry as a lucky loser:

• Viktoriya Tomova

Before the tournament

• Kiki Bertens → replaced by Aliaksandra Sasnovich
• Sorana Cîrstea → replaced by Kaja Juvan
• Fiona Ferro → replaced by Anna Kalinskaya
• Svetlana Kuznetsova → replaced by Kristýna Plíšková
• Magda Linette → replaced by Ajla Tomljanović
• Anastasia Pavlyuchenkova → replaced by Viktoriya Tomova
• Elena Rybakina → replaced by Polona Hercog
• Anastasija Sevastova → replaced by Tereza Martincová
• Laura Siegemund → replaced by Tímea Babos
• Donna Vekić → replaced by Andrea Petkovic
• Zheng Saisai → replaced by Nina Stojanović

• Ana Konjuh

Country	Player	Country	Player	Rank1	Seed
JPN	Shuko Aoyama	JPN	Ena Shibahara	26	1
HUN	Tímea Babos	RUS	Vera Zvonareva	45	2
CHN	Xu Yifan	CHN	Zhang Shuai	47	3
SRB	Aleksandra Krunić	SRB	Nina Stojanović	115	4

• ¹ Rankings as of May 10, 2021.

The following pairs received wildcards into the doubles main draw:

• Ivana Jorović / Lola Radivojević
• Elena Milovanović / Dejana Radanović

The following pair received entry into the doubles main draw using a protected ranking:

• Natela Dzalamidze / Irina Khromacheva

The following pair received entry as alternates:

• Camila Osorio / Emily Webley-Smith

Before the tournament

• Aliona Bolsova / Ankita Raina → replaced by Mihaela Buzărnescu / Ankita Raina
• Irina Khromacheva / Danka Kovinić → replaced by Natela Dzalamidze / Irina Khromacheva
• Elena Milovanović / Dejana Radanović → replaced by Camila Osorio / Emily Webley-Smith
• Anastasia Potapova / Vera Zvonareva → replaced by Tímea Babos / Vera Zvonareva

• Tournament overview on ATP Tour website
• Official website of the men's tournament
• Official website of the women's tournament