Sara Errani takes on Serena Williams in U.S. Open semifinals

FLUSHING, N.Y. -- On the small of Sara Errani's left wrist lays the delicate outline of a five-point star. Having it implanted on her left wrist was important, Errani says with a laugh, because one missed tattoo needle on her right arm might have spelled the end of her tennis career.

It's been two years since Errani deemed herself star-worthy, but it's little more than two months since she has become a real star.

After beginning the year ranked 45th in the WTA rankings and never having passed the third round at a major, the 25-year-old Italian has reached the quarterfinals of the Australian Open in January, the final of the French Open in June (where she upset two top-10 players before falling to Maria Sharapova 6-3, 6-2) and the semifinals of the U.S. Open, where she will meet seemingly unstoppable Serena Williams for a spot in the championship match.

Errani credits her recent ascent to a new, heavier, longer-handled Babalot racket that she began using at the start of this season. At 5-foot-4, she is diminutive compared with her fellow semifinalists -- 6-2 Sharapova, 6-0 Victoria Azarenka and 5-9 Williams -- but what she lacks in stature, she is quickly amassing in status.

Not only will Errani leave the U.S. Open ranked a career-high of at least No. 7 in the world (No. 6 if she reaches the final), she and her doubles partner, Roberta Vinci, just ascended to No. 1 in the world and will play for the women's doubles championships on Sunday. The team has already qualified for the year-end WTA Championships in Istanbul in late October.

"She's so different now," Vinci, the Texas Tennis Open champion, said of Errani, to whom she lost in straight sets in the U.S. Open quarterfinals. "She's more mature and more sure of herself. It's really unbelievable."

Against Williams, Errani will need every inch of her new racket, as well as her improved foot speed and new-found confidence. With titles this summer at Wimbledon, Stanford and the London Olympics, Williams enters the semifinals having won 24 of her last 25 matches. She has also dropped just 16 games in her first five Open matches, including a 6-0, 6-0 drubbing of Czech Andrea Hlavackova in the round of 16 and a 6-1, 6-3 defeat of 12th-seeded, former world No. 1 Ana Ivanovic in the quarters.

It is Williams' most dominating start to a U.S. Open semifinal since she lost just 14 games in her first five matches en route to the second of her three titles here in 2002.

Waiting on the top half of the draw will be either the top-seeded Azarenka or third-seeded Sharapova, both of whom have already claimed major titles this year, Azarenka at the Australian Open and Sharapova at the French Open. In what may be billed at the noisiest U.S. Open semifinal on record, Azarenka and Sharapova will hold nothing back, be it blistering double-handed backhands down the line or ear-splitting shrieks cross court.

Sharapova and Azarenka have already met in three finals this year with Azarenka winning twice on hard courts (including for the Australian Open title) and Sharapova winning on clay in Stuttgart earlier this summer.

As for Errani and Williams, their match might well be the Little Engine That Could taking on the Big Bad Bulldozer. But that doesn't mean that Williams is taking her opponent lightly.

"I can't underestimate her," said Williams, who turns 31 in two weeks but, unlike Andy Roddick, has no plans to retire anytime soon. "It's not by luck she's been doing so well. ...She's a great fighter and she has a great attitude and she believes. I think when you have such self-belief in yourself then you can do anything. I love her attitude. I do. I'm inspired by it actually."