ST. PETERSBURG, Russia — U.S. Open champion Stan Wawrinka took a step closer to a second straight title Friday as he advanced to the semifinals of the St. Petersburg Open.

The top-seeded Swiss took little more than an hour to dismiss Serbia's Viktor Troicki 7-5, 6-2 and set up a meeting with fourth-seeded Roberto Bautista Agut of Spain.

Third-seeded Tomas Berdych also reached the semifinals by beating Paolo Lorenzi of Italy 6-4, 6-3.

The ninth-ranked Czech will next face promising German youngster Alexander Zverev of Germany, who eased past Russian veteran Mikhail Youzhny 6-2, 6-2.

Earlier, Bautista Agut won his quarterfinal against Joao Sousa of Portugal 4-6, 6-1, 6-2.