2018 Diema Xtra Sofia Open – Singles

Grigor Dimitrov was the defending champion, but withdrew before the tournament because of a shoulder injury.

Mirza Bašić won his first ATP title, defeating Marius Copil in the final, 7–6(8–6), 6–7(4–7), 6–4.

Seeds
The top four seeds receive a bye into the second round. • # Stan Wawrinka (semifinals)

• #🇫🇷 Adrian Mannarino (second round)

• #🇱🇺 Gilles Müller (quarterfinals)

• #🇩🇪 Philipp Kohlschreiber (second round)

• # Robin Haase (first round)

• #🇷🇸 Viktor Troicki (quarterfinals)

• # João Sousa (second round)

• #🇷🇺 Evgeny Donskoy (first round)

Seeds
• # 🇩🇪 Florian Mayer (qualifying competition, lucky loser)

• # 🇧🇦 Mirza Bašić (qualified)

• # 🇩🇪 Oscar Otte (qualifying competition)

• # 🇸🇰 Martin Kližan (qualified)

• # 🇩🇪 Mats Moraing (first round)

• # 🇮🇹 Lorenzo Sonego (first round)

• # 🇮🇹 Salvatore Caruso (qualifying competition, lucky loser)

• # 🇸🇰 Jozef Kovalík (qualified)

Qualifiers
• # Ernests Gulbis

• # 🇧🇦 Mirza Bašić

• # 🇸🇰 Jozef Kovalík

• # 🇸🇰 Martin Kližan

Lucky losers
• # 🇩🇪 Florian Mayer

• # 🇮🇹 Salvatore Caruso