Stefanos Tsitsipas advanced to the second round of the U.S.Open after defeating France’s Alexander Muller in four sets (4-6, 6-0, 6-1, 7-6) Tuesday night.

After dropping the first set, the Greek, currently ranked 28th in the ATP world ranking, showed glimpses of his past form and talent and managed to win the next three sets comfortably.

The 27-year-old Greek had 12 more aces than his opponent, with 57% on his first serve and a notable 87% on his second serve.

The Greek player, who recently parted ways with the former coach of Novak Djokovic, Goran Ivanisevic, after the latter publicly pointed out Tsitsipas’s shortcomings, has struggled to string together consistent performances on the court. Tsitsipas rehired his father, Apostolos, as head coach, but his showing remains wanting.

Stefanos Tsitsipas will face Germany’s Daniel Altmaier in the second round.