STUTTGART, Germany - Serena Williams would happily forego the $100,000 prize money that goes to the winner of the Porsche Grand Prix in Stuttgart.

She'd much rather drive off in the bright red convertible parked courtside.

The tournament gives the winner a choice — either a cash prize or a low-slung Porsche 911 sports car. Williams, returning to action for the first time since beating Jelena Jankovic in the final of the U.S. Open three weeks ago and regaining the No. 1 ranking in the world, has no doubts about which she'd prefer.

"I've been trying for so long to win the Porsche, it's about time to take that 911 home,'' Williams said Monday.

Williams lost in the quarterfinals last year, to Svetlana Kuznetsova, and she could run into the Russian again at the same stage this week.

Both Williams sisters are in Stuttgart. Venus is seeded sixth and is in the different half of the draw, meaning the sisters cannot meet until the final.

Serena will also be seeking to defend her No. 1 ranking. Jankovic, who won the China Open Sunday, is only 21 points behind.

"I'm close to gaining the No. 1 spot again, but I'm just trying to focus on playing one match at a time and working on my game,'' Jankovic said in China. "I would love to come back to No. 1 and end the year at No. 1.''

Serena has the same goal.

"The U.S. Open is not the end of the year,'' Williams said. "I hope to do well in the last tournaments of the year.''

The nine-time Grand Slam champion had a first-round bye and will play Li Na in her opener. The Chinese player beat Nicole Vaidisova 6-1, 6-2 in the first match of the tournament Monday.

Jim Rogash / Getty Images The Week in Sports Pictures The nation grieved for those hurt, killed and affected by the Boston Marathon bombings. After one of the suspects was caught on Friday — following a day-long lockdown and manhunt — sports returned to Boston over the weekend.

Third-ranked Dinara Safina and No. 4 Elena Dementieva also could end the year as No. 1. The two and Jankovic also had first-round byes.

Ana Ivanovic and Maria Sharapova are the only top-10 players missing from the indoor tournament.

Last year's winner, Justine Henan, has retired.