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Singles
2021 Swiss Open Gstaad
Final
Champion	Casper Ruud
Runner-up	Hugo Gaston
Score	6–3, 6–2
Details
Draw	28 (4 Q / 3 WC )
Seeds	8
Events
Singles Doubles
← 2019 · Swiss Open Gstaad · 2022 →

Casper Ruud defeated Hugo Gaston in the final, 6–3, 6–2, to win the men's singles tennis title at the 2021 Swiss Open.^[1]

Albert Ramos Viñolas was the reigning champion from when the tournament was last held in 2019, but chose to compete in Umag instead.

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

	Semifinals							Final
	Q	Vít Kopřiva	3	0
	3	Casper Ruud	6	6
								3	Casper Ruud	6	6
									Hugo Gaston	3	2
		Hugo Gaston	3	6	6
	7	Laslo Đere	6	3	3

	First round							Second round							Quarterfinals							Semifinals
								1	D Shapovalov	6	3	2
	WC	J Nikles	2	1				Q	V Kopřiva	2	6	6
	Q	V Kopřiva	6	6											Q	V Kopřiva	6	6
		M Ymer	4	6	6											M Ymer	1	0
	LL	E Couacaud	6	3	3				M Ymer	66	79	6
		M-A Hüsler	4	6	5r			8	F López	78	67	4
	8	F López	6	4	6																	Q	V Kopřiva	3	0
																						3	C Ruud	6	6
								3	C Ruud	6	77
	LL	K Żuk	4	4					D Novak	4	65
		D Novak	6	6											3	C Ruud	6	5	6
		T Griekspoor	7	4	77										6	B Paire	2	7	3
		JI Londero	5	6	61				T Griekspoor	4	0r
		J Kovalík	3	62				6	B Paire	6	0
	6	B Paire	6	77

	First round							Second round							Quarterfinals							Semifinals
	5	F Delbonis	6	6
	WC	L Riedi	3	3				5	F Delbonis	0	77	63
		H Gaston	6	6					H Gaston	6	62	77
		JM Cerúndolo	4	2												H Gaston	6	1	713
		M Polmans	7	6											4	C Garín	4	6	611
	Q	S Ehrat	5	3					M Polmans	3	0
								4	C Garín	6	6
																							H Gaston	3	6	6
	7	L Đere	6	6																		7	L Đere	6	3	3
		T Seyboth Wild	4	3				7	L Đere	6	4	6
	Q	O Otte	63	1				Q	Z Bergs	2	6	2
	Q	Z Bergs	77	6											7	L Đere	6	65	6
		A Rinderknech	6	6												A Rinderknech	4	77	4
	WC	D Stricker	4	4					A Rinderknech	6	6
								2	R Bautista Agut	2	4

	First round							Qualifying competition
	1	Oscar Otte	6	6
		Andrea Pellegrino	2	4
								1	Oscar Otte	6	6
								8	Roberto Marcora	4	3
	Alt	Gonzalo Escobar	6	4	66
	8	Roberto Marcora	1	6	78

	First round							Qualifying competition
	2	Kacper Żuk	6	3	6
	Alt	Andrea Vavassori	3	6	2
								2	Kacper Żuk	6	4	2
								WC	Sandro Ehrat	2	6	6
	WC	Sandro Ehrat	6	6
	5	Ernests Gulbis	3	4

	First round							Qualifying competition
	3	Enzo Couacaud	6	6
		Pedro Sakamoto	1	3
								3	Enzo Couacaud	6	65	4
									Vít Kopřiva	2	77	6
		Vít Kopřiva	6	6
	6	Maximilian Marterer	2	3

	First round							Qualifying competition
	4	Steven Diez	6	6
	WC	Damien Wenger	2	4
								4	Steven Diez	65	4
									Zizou Bergs	77	6
		Zizou Bergs	77	6
	7	Aleksandar Vukic	65	3

• Main draw
• Qualifying draw