Serena will need time to get match tough

Unlike any other event, all signs are pointing to a return to play by Serena Williams at the Nasdaq-100 Open on Friday. She's on site and says she's eager to play.

Even if she's physically 100 percent, she still has to get her body into match shape and has to reacclimate to the mental side of the game. She should realize -- based on the difficulties her sister Venus Williams has gone through in her own injury comeback -- that this might be one of the biggest challenges of her career so far.

Although Serena's always supremely confident, she can't expect this return to be like her past injury layoffs. She's never had anything like this. It's really been almost nine months since she's hit a ball competitively.

So, she should be ready to face a lot of challenges. Plus, in Miami, she has the pressure of being the defending champion. Even though she's coming back into a field of women's tennis that is not at full strength (with Kim Clijsters the most recent addition to the list), it won't be easy.

In Serena's first few matches, watch her mobility -- anytime after knee surgery that's key, plus her athleticism is such a part of her game. Other things to keep an eye on are her unforced error count and steadiness off the ground. Is her power quotient the same?

Are the strengths she had beforehand -- like her strong serve -- still her strengths? Is she still hitting a big first serve and is her second serve as solid and smooth?

The time off and compensation for her injury could reveal new dimensions to her game. Will she come to net more to shorten the points?

One positive aspect is that the withdrawal of a fit Justine Henin-Hardenne (along with Lindsay Davenport) allowed Serena to be the No. 1 seed. It affords Serena some protection as the highest seed she could face before the semifinals is No. 7 Vera Zvonareva.

Additionally, Venus and Jennifer Capriati really have questions surrounding their match fitness and, really, their match fitness overall.

ESPN tennis analyst Pam Shriver won 21 singles and 112 doubles crowns, including 22 Grand Slam titles.