Singles
2021 Citi Open
Final
Champion	Jannik Sinner
Runner-up	Mackenzie McDonald
Score	7–5, 4–6, 7–5
Details
Draw	48 (6Q / 4WC)
Seeds	16
Events
Singles Doubles
← 2019 · Washington Open · 2022 →

Jannik Sinner defeated Mackenzie McDonald in the final, 7–5, 4–6, 7–5 to win the singles tennis title at the 2021 Citi Open. With the victory, Sinner became the youngest player and first teenager on the ATP Tour to win an ATP 500 title since the category was created in 2009.

Nick Kyrgios was the reigning champion from when the tournament was last held in 2019,^[1] but lost in the first round to McDonald.

All seeds receive a bye into the second round.

Click on the seed number of a player to go to their draw section.

	Quarterfinals							Semifinals							Final
	14	Lloyd Harris	3	5
		Kei Nishikori	6	7
									Kei Nishikori	4	6	5
									Mackenzie McDonald	6	3	7
		Mackenzie McDonald	6	6
		Denis Kudla	3	2
																Mackenzie McDonald	5	6	5
															5	Jannik Sinner	7	4	7
	5	Jannik Sinner	6	6
		Steve Johnson	4	2
								5	Jannik Sinner	77	6
								WC	Jenson Brooksby	62	1
	11	John Millman	1	2
	WC	Jenson Brooksby	6	6

	First round							Second round							Third round							Quarterfinals
								1/WC	R Nadal	6	4	77
	WC	J Sock	63	4				WC	J Sock	2	6	61
		Y Nishioka	77	0r											1/WC	R Nadal	4	6	4
		T Sandgren	6	2	6										14	L Harris	6	1	6
		J Duckworth	3	6	2				T Sandgren	4	0r
								14	L Harris	6	1
																						14	L Harris	3	5
																							K Nishikori	6	7
								9	A Bublik	2	5
		K Nishikori	6	6					K Nishikori	6	7
		S Querrey	4	3												K Nishikori	3	6	6
		M Giron	4	6	77										7	C Norrie	6	3	3
	Q	I Marchenko	6	4	61				M Giron	4	3
								7	C Norrie	6	6

	First round							Second round							Third round							Quarterfinals
								4	G Dimitrov	2	64
		E Gerasimov	5	4					I Ivashka	6	77
		I Ivashka	7	6												I Ivashka	4	4
		M McDonald	6	6												M McDonald	6	6
		N Kyrgios	4	4					M McDonald	66	6	6
								13	B Paire	78	4	4
																							M McDonald	6	6
																							D Kudla	3	2
								10	T Fritz	4	2
		D Kudla	6	65	6				D Kudla	6	6
	WC	F López	3	77	3											D Kudla	3	77	6
	WC	B Nakashima	6	6											WC	B Nakashima	6	63	4
		A Popyrin	3	3				WC	B Nakashima	77	6
								6	D Evans	61	0

	First round							Second round							Third round							Quarterfinals
								5	J Sinner	6	6
	Q	P Gunneswaran	6	1	1				E Ruusuvuori	2	4
		E Ruusuvuori	2	6	6										5	J Sinner	77	77
	Q	E Gómez	6	3	3										12	S Korda	63	63
		V Pospisil	4	6	6				V Pospisil	5	4
								12	S Korda	7	6
																						5	J Sinner	6	6
																							S Johnson	4	2
								15	M Kecmanović	3	2
	Q	M Krueger	64	2					R Berankis	6	6
		R Berankis	77	6												R Berankis	2	1
		S Johnson	6	77												S Johnson	6	6
	Q	R Ramanathan	3	60					S Johnson	65	6	6
								3	A de Minaur	77	4	2

	First round							Second round							Third round							Quarterfinals
								8	R Opelka	77	6
		T Paul	4	3					DE Galán	61	3
		DE Galán	6	6											8	R Opelka	3	64
	Q	E Ymer	3	7	6										11	J Millman	6	77
		J Thompson	6	5	3			Q	E Ymer	2	68
								11	J Millman	6	710
																						11	J Millman	1	2
																						WC	J Brooksby	6	6
								16	F Tiafoe	64	5
		K Anderson	64	3				WC	J Brooksby	77	7
	WC	J Brooksby	77	6											WC	J Brooksby	6	6
		Y Uchiyama	6	5	3										2	F Auger-Aliassime	3	4
		A Seppi	3	7	6				A Seppi	6	2	2
								2	F Auger-Aliassime	2	6	6

	First round							Qualifying competition
	Alt	Ramkumar Ramanathan	6	3	6
	Alt	Christopher Eubanks	4	6	3
								Alt	Ramkumar Ramanathan	7	6
								9	Sebastian Ofner	5	1
	PR	Tatsuma Ito	64	2
	9	Sebastian Ofner	77	6

	First round							Qualifying competition
	2	Liam Broady	6	2	6
	Alt	Mikael Torpegaard	4	6	3
								2	Liam Broady	4	60
								10	Emilio Gómez	6	77
	Alt	Matthew Ebden	3	1
	10	Emilio Gómez	6	6

	First round							Qualifying competition
	3/PR	J. J. Wolf	65	77	6
	WC	Ulises Blanch	77	63	3
								3/PR	J. J. Wolf	65	64
								11	Elias Ymer	77	77
		Bjorn Fratangelo	4	3
	11	Elias Ymer	6	6

	First round							Qualifying competition
	4	Maxime Cressy	6	7
		Michael Mmoh	2	5
								4	Maxime Cressy	5	77	3
								7	Illya Marchenko	7	64	6
	WC	Ivo Karlović	3	712	3
	7	Illya Marchenko	6	610	6

	First round							Qualifying competition
	5	Evgeny Donskoy	65	4
	Alt	Max Purcell	77	6
								Alt	Max Purcell	6	3	2
								12	Mitchell Krueger	3	6	6
	WC	Andrew Fenty	4	4
	12	Mitchell Krueger	6	6

	First round							Qualifying competition
	6	Prajnesh Gunneswaran	6	6
	WC	Luke Saville	2	2
								6	Prajnesh Gunneswaran	6	6
									Go Soeda	3	1
		Go Soeda	6	62	6
	8	Jason Jung	4	77	4

• Main draw
• Qualifying draw