RIYADH: In a clash of Grand Slam winners, Iga Swiatek swept aside Madison Keys in straight sets on the opening day of the WTA Finals in Riyadh on Saturday.

The Wimbledon champion needed just over an hour to beat Australian Open winner Keys 6-1, 6-2 at the season-ending tournament for the world's top eight players.

“I was in the zone from the beginning to the end, and I really wanted to keep it that way,” said Swiatek, who won 58 of 87 points.

It was Keys' first match in 68 days, since her first-round exit at the US Open. Swiatek, the 2023 WTA Finals champion, acknowledged such a long absence "can make you a bit rusty.”

Playing in the Serena Williams Group, Keys may need to beat Amanda Anisimova and Elena Rybakina to advance.

Rybakina beat Anisimova 6-3, 6-1 on Saturday.

The top two from each four-player group advance to the semi-final.

In the Stefanie Graf group are Aryna Sabalenka, defending champion Coco Gauff, Jessica Pegula and Jasmine Paolini.