The list of past Bank of the West Classic champions is littered with WTA legends, including Billie Jean King, Chris Evert, Martina Navratilova, Martina Hingis, Lindsay Davenport, and Kim Clijsters.

As the natural successor to those remarkable players, Serena Williams is the clear favorite to win this year at Stanford, especially since she has already won the event twice, along with this year’s Australian Open, French Open, and Wimbledon titles. The 21-time Grand Slam champion has also only lost one singles match all year – to Petra Kvitova at the Madrid Open in May – so she will be a formidable figure in Friday’s draw.

But she definitely won’t have things all her own way, for there are plenty of top-class women in the draw determined to stop the relentless American in her tracks.

Stanford first-timer Caroline Wozniacki could be Serena’s biggest threat. The Dane almost beat her in a final-set tie-break at the 2014 WTA Finals in Singapore and lost to her in straight sets in last year’s US Open final. Wozniacki recently claimed the level of fitness she achieved to run last year’s New York Marathon gives her an advantage over her rivals in long three-set matches. If a clash with Serena goes the distance, could the Dane emerge victorious this time?

Wozniacki’s long-time friend Agnieszka Radwanska, who reached the final in 2013, will also have her eyes on the title after an excellent recent run of form that culminated in reaching the Wimbledon semifinal. After losing to Garbine Muguruza in the last four at the All England Club, Radwanska said she was “very happy” with her game and pleased with her grass-court season. A strong showing in Stanford would be an excellent way for the Polish No. 1 to start the hard court season.

One woman who unfortunately will not be competing in the BOTW Classic is Wimbledon finalist Garbine Muguruza, who has been forced to pull out with an abdominal strain. She said, “Unfortunately the long European swing has taken its toll on my body. My abdominal strain has not fully healed and will need some weeks to get ready for the US swing.” Muguruza had a taste of glory at Stafnrod last year when she won the doubles title with compatriot Carla Suarez Navarro, who could challenge Serena for this year’s singles title. The diminutive Spaniard with the superb single-handed backhand has reached two WTA Premier finals and boasts an impressive 35-14 win-loss record in 2015, so she will certainly expect to reach the latter stages of this tournament.

Three notable Germans at the tournament are led by Angelique Kerber, who lost 7-6 6-3 to Serena in last year’s final. The German No. 1 won the Aegon Classic in June in impressive style but dropped ranking points at Wimbledon by losing to an inspired Muguruza in the third round. Kerber is joined in the draw by compatriot Andrea Petkovic, whose impressive results in the last 16 months have seen her rise from 40th to 16th in the world rankings. Petkovic was in excellent form last year at Stanford, defeating Venus Williams 6-1 3-6 7-5 in the quarterfinals before succumbing to Serena 7-5 6-0 in the semifinals. Completing the German triple threat in the draw is Sabine Lisicki, who always promises much with her record-breaking serve and thunderous forehand but frequently fails to deliver. The current German No. 3 was defeated in the first round last year by Ana Ivanovic.

Some of the brightest young stars in women’s tennis represent outside bets for this year’s Bank of the West Classic. Chief among them is Karolina Pliskova, age 23, who won her fourth WTA title in Prague in April and has risen over 50 places in the world rankings during a sensational last 15 months. And home fans will be rooting for the 20-year-old Madison Keys, whom many pundits have tipped to be a future Grand Slam champion. The world No. 18 has had a patchy 2015, playing superbly to reach an Australian Open semifinal, a Wimbledon quarterfinal, and the Charleston final, but losing early in most of her other tournaments.

The 17th-ranked Elina Svitolina, also 20, won her first WTA title almost exactly two years ago in Baku to break into the world’s top 50. Another exciting young gun, 21-year-old Caroline Garcia, was famously tipped for future Grand Slam glory by Andy Murray, but she has yet to live up to that promise. Her powerful game nevertheless makes her one to avoid in Friday’s draw.

With such a high-quality field playing in excellent facilities at Stanford University, the 2015 edition of the Bank of the West Classic promises to be a fantastic tournament. Can anyone stop Serena?