2021 Sibiu Open – Singles

Marc-Andrea Hüsler was the defending champion but lost in the semifinals to Thanasi Kokkinakis.

Stefano Travaglia won the title after defeating Kokkinakis 7–6(7–4), 6–2 in the final.

Seeds
• # 🇮🇹 Stefano Travaglia (champion)

• # 🇲🇩 Radu Albot (first round)

• # 🇸🇰 Alex Molčan (quarterfinals)

• # 🇧🇦 Damir Džumhur (second round)

• # 🇨🇿 Zdeněk Kolář (quarterfinals)

• # Marc-Andrea Hüsler (semifinals)

• # 🇦🇺 Thanasi Kokkinakis (final)

• # 🇮🇳 Sumit Nagal (semifinals)