STUTTGART, Germany — Serena Williams made a successful return to the Porsche Grand Prix, overwhelming Zuzana Ondruska 6-0, 6-0 in the first round Tuesday.

"I think I played really well. Most of all I am excited to be back at the tournament," the sixth-seeded Williams said.

Williams, who has rarely traveled to Europe in the fall, last played at the Porsche Grand Prix in 1999.

Ondruska, ranked No. 140 in the world, was a late replacement for Elena Bovina, who pulled out with a left-ankle injury.

Earlier, 18-year-old Agnieszka Radwanska defeated Wimbledon runner-up Marion Bartoli 0-6, 6-2, 6-1.

The Polish teenager, who won her first title last month in Stockholm, won nine straight games after going down 2-1 in the second set.

"I wish I could have played better on my birthday, but the court is very slow," said Bartoli, who turned 23 on Tuesday.

Radwanska grabbed attention by beating defending champion Maria Sharapova in the third round of the U.S. Open.

"I woke up after the first set, I knew I had to change something, the first set went so fast," Radwanska said.

Defending champion Nadia Petrova also came from behind to beat German wild card Tatjana Malek 2-6, 6-1, 6-1.

The seventh-seeded Russian looked rusty in the first set, but then recovered against the German teen.

"I haven't played much in the last four weeks so I had trouble adjusting to the conditions," Petrova said.

Shahar Peer of Israel also won, defeating Francesca Schiavone of Italy 6-1, 7-6 (6).

Peer earned match point in the tiebreaker when Schiavone committed one of her five double-faults.

Eight of the top 10 players are taking part in the indoor event, with only Sharapova and Venus Williams absent.