ATLANTA (AP) — Jack Sock of the United States beat Colombia's Alejandro Gonzalez 6-2, 6-4 in the first round of the Atlanta Open on Tuesday.

Sock finished off Gonzalez in 1 hour, 6 minutes by winning 89 percent of his quality first serves, and relying on his forehand to break Gonzalez's serve twice in the first set and once in the second.

Eight of the first nine first-round matches lasted two sets Tuesday.

In the only three-set match, Robby Ginepri fought off eight of 11 break points to beat Sergiy Stakhovsky of Ukraine 7-6, 3-6, 6-0.

No. 6-seeded Denis Istomin of Uzbekistan beat Rajeev Ram 6-1, 6-4, eight-seeded Marinko Matosevic of Australia downed Victor Estrella Burgos of the Dominican Republic, 6-0, 6-2 and Slovakia's Lukas Lacko beat Nathan Pasha 6-2, 7-5.

Tim Smyczek beat fellow American Ryan Harrison 6-0, 6-2, while Benjamin Becker of Germany defeated Australia's Matthew Ebden 6-4, 6-2.

Sock and partner Vasek Popisil won the doubles title at Wimbledon earlier this month, upsetting the top-ranked team of Mike and Bob Bryan in the finals.

The 21-year-old Sock said doubles success on the greatest stage in tennis has boosted his singles game.

"At Wimbledon, Vasek and I were in a lot of tough positions. We were able to pull through them and get out of there, and you have that in the back of your mind, and that sense of confidence that you can battle through a lot of things."