PARIS - American Jack Sock made a successful French Open debut yesterday while wearing initials on his shoes in honor of two friends who he said died recently in separate accidents.

Sock, a 20-year-old from Lincoln, Neb., beat Guillermo Garcia-Lopez, 6-2, 6-2, 7-5, and acknowledged mixed emotions afterward. He said one of the accident victims was a former high school teammate, and the other was a friend he played with in juniors tournaments.

"They were both 21, I think - sophomores, juniors in college," Sock said. "Kind of hits you out of nowhere. I was definitely thinking of them out there."

Ranked 118th, Sock reached the main draw by winning three matches in qualifying. He has an unimpressive record on the green clay common in the United States but said Europe's red clay is different, and he likes it better.

"I'll always look forward to coming back here," he said. "Growing up I didn't play a whole lot on it, but I loved playing on it when I did. Coming over here and playing on the real stuff has been great."

Sock hasn't taken to the local cuisine, however. Instead he frequents a Mexican restaurant that is part of a U.S. chain.

"I'll be there as much as I can," he said. "It's a decent cab ride from the hotel. I think I have been there six or seven out of 10 nights probably."

Sock made his first Grand Slam splash last August at the U.S. Open, where he won two matches. He's part of a new generation of U.S. players who have enjoyed some success in the first round at Roland Garros, even though clay is traditionally the worst surface for Americans.

Despite losses yesterday by Lauren Davis and CoCo Vandeweghe, U.S. women are 9-5 in the opening round, with Jamie Hampton's match against No. 25 Lucie Safarova postponed until today because of rain.

Also, No. 1-ranked Novak Djokovic, embarking on a bid to complete a career Grand Slam, pulled out a tight first set en route to a 7-6 (5), 6-4, 7-5 victory in the first round against David Goffin, a Belgian who was the surprise of Roland Garros a year ago. Sam Stosur, the 2010 French Open runner-up, waited 2 1/2 hours to play because of rain, then quickly won her opening match, drubbing 42-year-old Kimiko Date-Krumm, 6-0, 6-2.