Without the Williamses, who steps up?

Maria Sharapova puts her shoulder to the test in her first action since August. Elsa/Getty Images

With the Williams sisters refusing to play in Indian Wells, the other top-tier women seek to take advantage at the biggest event since the Australian Open. Here are five story lines to keep an eye on:

Sharapova's serve

Off the tour since August, Maria Sharapova will return this week in Indian Wells -- sort of. She'll play doubles and partner with Elena Vesnina, which will allow only limited judgments about her movement and consistency but should be enough to see whether she's swinging freely after shoulder surgery in October.

Coincidentally, it was at Indian Wells a year ago when Sharapova reinjured the shoulder, although the problem was not correctly diagnosed until after Montreal. The major thing to watch for in the Russian's comeback match will be her serve, which often has been a harbinger of her health. Shoulder troubles in 2007 led to a major case of double faults and a temporarily changed service motion; renewed problems with the joint manifested themselves again in her serve during the summer, particularly at Wimbledon.

The serve also is the stroke that spent the longest time on ice following her surgery. As Sharapova wrote on her Web site in early February, "Yesterday I played my first few points with serves in about six months, which was pretty exciting!

"You are never really going to forget how to hit a tennis ball, but what you do forget is how much work and repetition you must put into every single day in order to get back to where you were."

Ivanovic's assurance

The glare of publicity and a thumb injury knocked Ana Ivanovic off track in the middle of last year, and she has had trouble rediscovering her comfort zone ever since. Focusing more on trying to improve her defense and lacking confidence after a string of early defeats, Ivanovic seemed to be retreating into a less aggressive game that downplayed her biggest weapons -- a solid serve and a big forehand.

After working on and off with Adidas coach Sven Groeneveld for the past couple of years, Ivanovic hired Craig Kardon just before Dubai and looks to be trying to reassert herself on the court.

"He is very positive and I like his coaching philosophy so far," Ivanovic wrote about Kardon on her Web site. "For example, he is more concerned with tactics and dominating opponents instead of looking closely at technique and videos; I think this suits me."

The defending Indian Wells champion is seeded fifth and could face Elena Dementieva in the quarterfinals. After that would be a possible rematch of last year's semifinal with Jelena Jankovic, a semifinal matchup that would serve as a good yardstick for judging both Serbs. If they can make it that far, that is.

A glimpse of a Williams?

Indian Wells is now one of four mandatory events on the Sony Ericsson WTA calendar, but the Williams sisters emphatically maintain their boycott. Neither has played the event since 2001, when Venus withdrew from a semifinal match between the sisters and resentful fans booed Serena during the final.

Earlier this year, Serena even went so far as to say she would play only the tour's "nonracist mandatories," a pointed reference to the alleged racial insults made by some members of the crowd during the incident.

But there have been reports that Venus plans to attend the WTA meeting that will take place during the tournament. There are weighty matters to be discussed, including Shahar Peer's visa denial in Dubai and various money matters related to the impact of the financial crisis on tournaments.

To avoid a suspension for missing a mandatory event, the Williams sisters must do some promotional work within the tournament vicinity during the next 12 months. Nearby Los Angeles is included in that geographical definition.

The fight for No. 3

With or without the sanction of the rankings, Serena and Venus have firmly established themselves as the current top two in the women's game. Below them, however, it's strictly a matter of conjecture.

Jankovic ended last year as No. 1 but is struggling this season after bulking up during the Christmas break and then being hit by a virus in January. (Sound familiar?) The illness doesn't seem to have been particularly severe in her case, but she has overplayed for the past couple of years and has not been able to establish any rhythm in 2009. "I haven't played much this year, and I'm just trying to get back in shape and in form and trying to find my game," she said ahead of the BNP Paribas Open exhibition in Madison Square Garden last week.

Dinara Safina, officially the world No. 2, hasn't been able to win finals recently and put up a particularly poor showing against Serena at the Aussie Open in Melbourne. Dementieva, at No. 4, made an excellent start to the year but can't seem to win against the big names at big events outside of the Olympics. And Ivanovic, as mentioned, has fallen even further behind.

An Indian Wells title wouldn't erase the fact that their combined record against the Williams sisters since the French Open is 3-12. But if one of the four earns an emphatic win, she would take a big step toward establishing herself as the best of the rest.

The teens' nerves

Nineteen-year-olds such as Caroline Wozniacki, Victoria Azarenka and Alize Cornet as well as just-turned-20 Agnieszka Radwanska have been winning their share of titles and making their way up the rankings. But what they haven't done is pull off any really significant upsets, as they've choked away several recent chances.

Finally, putting away a top-five player would be a definite sign that they're ready to move up into the upper echelon themselves. They won't lack opportunity at Indian Wells.

Wozniacki has a golden opening, with only the vulnerable Svetlana Kuznetsova and Vera Zvonareva in her path to the semifinals. Azarenka has a potential meeting with top seed Safina in the quarterfinals, while Radwanska and Cornet might have to battle each other in the round of 16 before having a chance to face Jankovic in the quarters.

Another talented teen will have a chance to meet Jankovic even earlier. Surging 17-year-old Anastasia Pavlyuchenkova could face the second seed in the second round.

Kamakshi Tandon is a freelance tennis writer for ESPN.com.