2021 St. Petersburg Open – Singles

Andrey Rublev was the defending champion, but lost in the quarterfinals to Botic van de Zandschulp.

Singles
2021 St. Petersburg Open
Champion	Marin Čilić
Runner-up	Taylor Fritz
Score	7–6(7–3), 4–6, 6–4
Draw	28 (4 Q / 3 WC )
Seeds	8

Main article: 2021 St. Petersburg Open

Marin Čilić won the title, defeating Taylor Fritz in the final, 7–6^(7–3), 4–6, 6–4.

Seeds

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

1. Andrey Rublev (quarterfinals)
2. Denis Shapovalov (quarterfinals)
3. Roberto Bautista Agut (quarterfinals)
4. Aslan Karatsev (second round)
5. Taylor Fritz (final)
6. Karen Khachanov (second round)
7. Alexander Bublik (second round)
8. Sebastian Korda (second round)

Draw

Key

• Q = Qualifier
• WC = Wild card
• LL = Lucky loser
• Alt = Alternate
• SE = Special exempt
• PR = Protected ranking
• ITF = ITF entry
• JE = Junior exempt
• w/o = Walkover
• r = Retired
• d = Defaulted
• SR = Special ranking

Finals

	Semifinals							Final
	Q	Botic van de Zandschulp	3	3
		Marin Čilić	6	6
									Marin Čilić	77	4	6
								5	Taylor Fritz	63	6	4
	5	Taylor Fritz	5	6	6
		Jan-Lennard Struff	7	1	3

Top half

	First round							Second round							Quarterfinals							Semifinals
								1	A Rublev	6	6
		L Đere	3	2					I Ivashka	4	4
		I Ivashka	6	6											1	A Rublev	3	4
	Q	B van de Zandschulp	6	6											Q	B van de Zandschulp	6	6
	Q	Y Nishioka	2	2				Q	B van de Zandschulp	6	7
	WC	N Serdarušić	62	5				8	S Korda	2	5
	8	S Korda	77	7																		Q	B van de Zandschulp	3	3
																							M Čilić	6	6
								3	R Bautista Agut	6	6
	Q	E Gerasimov	5	4					M McDonald	3	2
		M McDonald	7	6											3	R Bautista Agut	4	6	3
		M Čilić	6	6												M Čilić	6	3	6
		A Ramos Viñolas	2	3					M Čilić	6	61	6
		A Mannarino	3	3				6	K Khachanov	4	77	4
	6	K Khachanov	6	6

Bottom half

	First round							Second round							Quarterfinals							Semifinals
	5	T Fritz	6	6
	Q	E Ruusuvuori	1	4				5	T Fritz	77	6
		P Martínez	3	2					T Paul	63	4
		T Paul	6	6											5	T Fritz	6	6
		J Millman	6	6												J Millman	4	2
	WC	Y Oliel	1	1					J Millman	6	6
								4	A Karatsev	3	2
																						5	T Fritz	5	6	6
	7	A Bublik	6	6																			J-L Struff	7	1	3
	WC	E Tiurnev	3	4				7	A Bublik	4	3
		J-L Struff	77	6					J-L Struff	6	6
		J Duckworth	63	3												J-L Struff	6	6
		F Delbonis	2	61											2	D Shapovalov	4	3
	PR	P Andújar	6	77				PR	P Andújar	6	3	0
								2	D Shapovalov	2	6	6

Qualifying

Seeds

1. Botic van de Zandschulp (qualified)
2. Benjamin Bonzi (first round)
3. Federico Coria (first round)
4. Miomir Kecmanović (qualifying competition)
5. Emil Ruusuvuori (qualified)
6. Yoshihito Nishioka (qualified)
7. Mikael Ymer (first round)
8. Egor Gerasimov (qualified)

Qualifiers

1. Botic van de Zandschulp
2. Emil Ruusuvuori
3. Egor Gerasimov
4. Yoshihito Nishioka

Qualifying draw

First qualifier

	First round							Qualifying competition
	1	Botic van de Zandschulp	6
	Alt	Marc Polmans	6r
								1	Botic van de Zandschulp	5	6	6
								Alt	Evgeny Donskoy	7	3	2
	Alt	Evgeny Donskoy	6	7
	7	Mikael Ymer	2	5

Second qualifier

	First round							Qualifying competition
	2	Benjamin Bonzi	6	64	2
	WC	Dmitry Popko	4	77	6
								WC	Dmitry Popko	62	4
								5	Emil Ruusuvuori	77	6
	PR	Gilles Simon	0	3
	5	Emil Ruusuvuori	6	6

Third qualifier

	First round							Qualifying competition
	3	Federico Coria	3	4
		Radu Albot	6	6
									Radu Albot	62	4
								8	Egor Gerasimov	77	6
		Damir Džumhur	1	66
	8	Egor Gerasimov	6	78

Fourth qualifier

	First round							Qualifying competition
	4	Miomir Kecmanović	2	6	6
	WC	Evgeny Karlovskiy	6	4	1
								4	Miomir Kecmanović	3	6	2
								6	Yoshihito Nishioka	6	4	6
	Alt	Roman Safiullin	5	2
	6	Yoshihito Nishioka	7	6

References

• Main draw
• Qualifying draw