2021 Lisboa Belém Open – Men's singles

Jaume Munar was the defending champion^[1] but chose not to defend his title.

Men's singles
2021 Lisboa Belém Open
Champion	Dmitry Popko
Runner-up	Andrea Pellegrino
Score	6–2, 6–4

Main article: 2021 Lisboa Belém Open

Dmitry Popko won the title after defeating Andrea Pellegrino 6–2, 6–4 in the final.

Seeds

1. Thiago Monteiro (second round)
2. Taro Daniel (first round)
3. Hugo Gaston (semifinals)
4. Andrej Martin (semifinals, retired)
5. Nikola Milojević (quarterfinals)
6. Cedrik-Marcel Stebe (quarterfinals, retired)
7. Alessandro Giannessi (withdrew)
8. Dmitry Popko (champion)

Draw

Key

• Q = Qualifier
• WC = Wild card
• LL = Lucky loser
• Alt = Alternate
• ITF = ITF entry
• PR = Protected ranking
• SR = Special ranking
• SE = Special exempt
• JE = Junior exempt
• JR = Junior Accelerator Programme entrant
• CO = College Accelerator Programme entrant
• NG = Next Gen Accelerator Program entrant
• w/o = Walkover
• r = Retired
• d = Defaulted

Finals

	Semifinals							Final
		Andrea Pellegrino	77	1
	4	Andrej Martin	65	0r
									Andrea Pellegrino	2	4
								8	Dmitry Popko	6	6
	3	Hugo Gaston	3	4
	8	Dmitry Popko	6	6

Top half

	First round							Second round							Quarterfinals							Semifinals
	1	T Monteiro	6	6
		A Müller	4	4				1	T Monteiro	3	68
		I Sijsling	0	4					A Pellegrino	6	710
		A Pellegrino	6	6												A Pellegrino	6	6
		F Ferreira Silva	6	6												F Ferreira Silva	3	1
		T Lamasine	3	4					F Ferreira Silva	63	6	6
		G Zeppieri	4	6	6				G Zeppieri	77	4	0
	Q	S Rodríguez Taverna	6	3	4																		A Pellegrino	77	1
	4	A Martin	4	6	6																	4	A Martin	65	0r
		R Cid Subervi	6	4	0			4	A Martin	2	6	6
	WC	G Oliveira	77	6				WC	G Oliveira	6	4	3
	WC	Pedro Araújo	64	4											4	A Martin	6	6
	PR	E Benchetrit	2	2											5	N Milojević	4	4
		C Lestienne	6	6					C Lestienne	5	4
	Q	S Fanselow	4	4				5	N Milojević	7	6
	5	N Milojević	6	6

Bottom half

	First round							Second round							Quarterfinals							Semifinals
	6	C-M Stebe	6	6
	LL	J Berrettini	0	1				6	C-M Stebe	4	77	6
		M Geerts	6	3	4				N Borges	6	64	4
		N Borges	4	6	6										6	C-M Stebe	63	3r
		R Haase	6	4	6										3	H Gaston	77	4
		F Baldi	4	6	4				R Haase	6	65	3
		F Forti	3	1				3	H Gaston	4	77	6
	3	H Gaston	6	6																		3	H Gaston	3	4
	8	D Popko	1	6	4																	8	D Popko	6	6
		L Giustino	6	3	1r			8	D Popko	6	6
		A Arnaboldi	2	6	68			Q	B Hassan	2	4
	Q	B Hassan	6	3	710										8	D Popko	64	7	6
		J Domingues	6	6												J Domingues	77	5	0
	WC	T Cação	4	4					J Domingues	6	6
	Q	D Michalski	77	5	6			Q	D Michalski	2	2
	2	T Daniel	64	7	2