GSTAAD: Top seed Mikhail Youzhny opened his title defense at the Crédit Agricole Suisse Open Gstaad on Thursday with a 6-3, 6-4 second-round victory over Kenny de Schepper.

The Russian won the ninth of his 10 ATP World Tour titles last year with victory over Robin Haase in the final. Youzhny advanced in 70 minutes on his return, winning 75 percent of his service points and breaking de Schepper twice from seven opportunities.

The 32-year-old Youzhny improved to an 11-14-match record on the season and goes on to face either seventh seed Haase or Swiss wild card Henri Laaksonen.

Argentine duo Facundo Bagnis and Federico Delbonis upset top seeds and defending champions Jamie Murray and John Peers 5-7, 6-4, 11-9 in 80 minutes. Bagnis and Delbonis are playing their fourth event of the season together, highlighted by a semifinal showing in Sao Paulo

Pospisil, Sock in quarters

In Atlanta, Canadian fourth seed Vasek Pospisil and American Jack Sock, who combined to win the Wimbledon doubles title, advanced to the ATP Atlanta Open quarterfinals with straight-set victories Wednesday.

Pospisil fired 10 aces to defeat Ukraine’s Illya Marchenko 7-5, 6-3 in 93 minutes while Sock beat New Zealand qualifier Michael Venus 6-4, 6-2 at the $568,000 hardcourt event, an early US Open warm-up tournament.

“It wasn’t easy. It was very hot and humid,” Pospisil said. “It was difficult to find a balance between saving my energy and being focused. I think I balanced both really well. I won the big points. That was key.” Sock saved the only two break points he faced and won 27 of 29 points on his first serve to win in 67 minutes. Sock will next face Slovakian Lukas Lacko, who rallied to oust Uzbek sixth seed Denis Istomin 5-7, 6-1, 6-4.

Pospisil booked a last-eight date with Israel’s Dudi Sela, who eliminated American Sam Querrey 6-2, 6-4.

Taiwan seventh seed Lu Yen-Hsun took a 6-4, 6-4 first-round victory over American Alex Kuznetsov. He faces German Benjamin Becker next.