2021 Singapore Tennis Open – Singles

Alexei Popyrin defeated Alexander Bublik 4–6, 6–0, 6–2 to claim his first ATP Tour Men's Singles tennis title at the 2021 Singapore Open. The Singapore Tennis Open was a new addition to the ATP Tour in 2021

Seeds
The top four seeds receive a bye into the second round. • # 🇫🇷 Adrian Mannarino (quarterfinals)

• # 🇦🇺 John Millman (second round)

• # Marin Čilić (semifinals)

• # 🇰🇿 Alexander Bublik (final)

• # 🇯🇵 Yoshihito Nishioka (quarterfinals)

• # 🇲🇩 Radu Albot (semifinals)

• # Lloyd Harris (first round)

• # 🇰🇷 Kwon Soon-woo (quarterfinals)

Seeds
• # 🇺🇸 Thai-Son Kwiatkowski (qualified)

• # 🇮🇹 Matteo Viola (qualifying competition)

• # 🇺🇸 Christopher Eubanks (qualified)

• # 🇹🇳 Malek Jaziri (qualifying competition)

• # 🇹🇷 Altuğ Çelikbilek (qualified)

• # 🇦🇺 John-Patrick Smith (qualified)

• # 🇮🇹 Alessandro Bega (qualifying competition)

• # 🇺🇦 Vladyslav Orlov (first round)

Qualifiers
• # 🇺🇸 Thai-Son Kwiatkowski

• # 🇹🇷 Altuğ Çelikbilek

• # 🇺🇸 Christopher Eubanks

• # 🇦🇺 John-Patrick Smith