Britain's Cameron Norrie is through to the second round of the St Petersburg Open in Russia after beating Taylor Fritz.
The 25-year-old overcame the American, who is ranked 47 places above him in the world at 28th, 6-4 4-6 6-3.
Norrie will play either Mikhail Kukushkin of Kazakhstan or Serbia's Miomir Kecmanovic in the last 16.
Stefanos Tsitsipas withdrew from the tournament because of a "minor" leg injury picked up at the French Open.
"Following my doctor's feedback, I decided to withdraw from St Petersburg, take a week off and prepare for Vienna," said Tsitsipas on social media.