Alexander Zverev continued his search for a first Grand Slam title with victory over Alexandre Muller to reach the US Open third round.
Germany's Zverev, 27, reached the final in New York in 2020 as well as the French Open final earlier this year.
However, he lost the US Open showpiece to Dominic Thiem from two sets up, and led Carlos Alcaraz by two sets to one in Paris before succumbing to the Spaniard.
Zverev said he had doubts he could return to the top level after suffering a serious ankle injury at the French Open in 2022.