LONDON (AP) ― Juan Martin del Potro got past Richard Gasquet to win his opening round-robin match at the ATP World Tour Finals on Monday.

Stanislas Wawrinka grabbed the spotlight with a win in his maiden appearance at the season-ending tournament.

After Wawrinka defeated Tomas Berdych 6-3, 6-7 (0), 6-3 in Group A, Del Potro beat Gasquet 6-7 (4), 6-3, 7-5 to secure crucial points in a tough Group B that also includes Roger Federer and Novak Djokovic, who will be facing off on Tuesday.

After the round-robin stage, the top two finishers in each group advance to the semifinals.

Playing in the tournament for the first time since 2007, Gasquet produced some stunning shots but struggled to return del Potro’s big serve in a match laced with unforced errors and winners from both sides.

Gasquet said he was disappointed by the result, his sixth loss in seven matches against Del Potro, but took some comfort in the way he lost.

“The level is very high. So every match is a final for me,” Gasquet said. “Tonight I played well, I was really close.”

Del Potro, who hit 35 winners and made 40 unforced errors, was relieved to come out on top ahead of two difficult matches.

“This tournament means a lot to me,” he said.