ST. PETERSBURG, Russia — Stan Wawrinka is back on court after winning the U.S. Open, and he's kept up his winning ways.

The Swiss world No. 3 needed just 57 minutes to win 6-3, 6-1 against Czech player Lukas Rosol in the second round of the St. Petersburg Open on Wednesday after receiving a first-round bye.

Wawrinka said "it was a great level from myself for the first one" and that he felt "really focused" against Rosol, who is ranked 85th.

Wawrinka next plays one of two Serbians, either seventh-seeded Viktor Troicki, who beat Portugal's Gastao Elias 6-1, 6-2 in the first round earlier Wednesday, or the unseeded Dusan Lajovic.

Also Wednesday, eighth-seeded Joao Sousa of Portugal won 3-6, 6-4, 7-5 in the first round against Moldovan qualifier Radu Albot.