2021 Internazionali di Tennis Città di Trieste – Singles

Carlos Alcaraz was the defending champion but chose not to defend his title.

Tomás Martín Etcheverry won the title after defeating Thiago Agustín Tirante 6–1, 6–1 in the final.

Seeds
• # 🇧🇦 Damir Džumhur (semifinals)

• # 🇫🇷 Antoine Hoang (second round)

• # 🇦🇷 Tomás Martín Etcheverry (champion)

• # 🇷🇸 Danilo Petrović (withdrew)

• # 🇮🇹 Alessandro Giannessi (second round)

• # 🇦🇷 Marco Trungelliti (first round, retired)

• # 🇩🇪 Maximilian Marterer (semifinals)

• # 🇮🇹 Thomas Fabbiano (first round)