Singles
2021 MercedesCup
Final
Champion	Marin Čilić
Runner-up	Félix Auger-Aliassime
Score	7–6(7–2), 6–3
Details
Draw	28
Seeds	8
Events
Singles Doubles
← 2019 · Stuttgart Open · 2022 →

Marin Čilić defeatedFélix Auger-Aliassime in the final, 7–6^(7–2), 6–3 to win the singles tennis title at the 2021 Stuttgart Open. It was Čilić's 19th careerATP Tour singles title, his first in three years, and he did not drop aset en route to the victory. The No. 47-ranked, 32-year-old Čilić also became the lowest-ranked winner sinceJuan Carlos Ferrero in2011 and the third-oldest champion in tournament history. Defending finalist Auger-Aliassime was contesting for his first career singles title in his eighth final.^[1]

Matteo Berrettini was the reigning champion from when the event was last held in2019,^[2] but he could not participate as he was still competing at theFrench Open upon the beginning of the tournament.

The top fourseeds received abye into the second round.

Key

	Semifinals							Final
		Marin Čilić	6	1
	WC	Jurij Rodionov	3	0r
									Marin Čilić	77	6
								3	Félix Auger-Aliassime	62	3
	3	Félix Auger-Aliassime	6	7
		Sam Querrey	4	5

	First round							Second round							Quarterfinals							Semifinals
								1	D Shapovalov	6	62	6
		F López	6	6					F López	2	77	3
		A Popyrin	4	4											1	D Shapovalov	5	63
		M Čilić	7	6												M Čilić	7	77
	WC	R Molleker	5	3					M Čilić	6	6
	WC	D Brown	3	64				5	N Basilashvili	3	2
	5	N Basilashvili	6	77																			M Čilić	6	1
																						WC	J Rodionov	3	0r
								4	A de Minaur	68	6	6
		G Pella	3	4					J Thompson	710	3	4
		J Thompson	6	6											4	A de Minaur	6	3	64
		D Koepfer	6	3	2										WC	J Rodionov	3	6	77
	WC	J Rodionov	2	6	6			WC	J Rodionov	5
	Q	P Gojowczyk	5	6	6			Q	P Gojowczyk	3r
	LL	I Ivashka	7	4	2

	First round							Second round							Quarterfinals							Semifinals
	6	U Humbert	6	6
		M Fucsovics	3	1				6	U Humbert	711	6
		J Chardy	4	4				WC	Y Hanfmann	69	2
	WC	Y Hanfmann	6	6											6	U Humbert	65	68
		G Simon	4	5											3	F Auger-Aliassime	77	710
		L Harris	6	7					L Harris	3	64
								3	F Auger-Aliassime	6	77
																						3	F Auger-Aliassime	6	7
	7	A Mannarino	3	2																			S Querrey	4	5
	Q	J Duckworth	6	6				Q	J Duckworth	4	67
	Q	A Çelikbilek	4	1					S Querrey	6	79
		S Querrey	6	6												S Querrey	64	77	6
	Q	R Albot	64	65											WC	DS Stricker	77	64	3
	WC	DS Stricker	77	77				WC	DS Stricker	77	77
								2	H Hurkacz	65	65

	First round							Qualifying competition
	Alt	Luke Saville	78	4	4
	Alt	James Duckworth	66	6	6
								Alt	James Duckworth	77	3	7
								8	Ilya Ivashka	65	6	5
	WC	Daniel Masur	0	64
	8	Ilya Ivashka	6	77

	First round							Qualifying competition
	Alt	Sergiy Stakhovsky	1	64
	Alt	Peter Gojowczyk	6	77
								Alt	Peter Gojowczyk	6	6
								Alt	Grégoire Barrère	2	4
	Alt	Grégoire Barrère	6	6
	5	Marcos Giron	3	2

	First round							Qualifying competition
	3	Jiří Veselý	77	2	4
	Alt	Dennis Novak	65	6	6
								Alt	Dennis Novak	6	63	5
								Alt	Altuğ Çelikbilek	1	77	7
	Alt	Altuğ Çelikbilek	6	2	6
	6	Lucas Pouille	3	6	3

	First round							Qualifying competition
	4	Emil Ruusuvuori	7	6
	Alt	João Sousa	5	3
								4	Emil Ruusuvuori	65	4
								7	Radu Albot	77	6
	Alt	Christopher O'Connell	3	0r
	7	Radu Albot	6	0

• Main draw
• Qualifying draw

• 2021 ATP Tour
• Stuttgart Open

• Articles with short description
• Short description is different from Wikidata