Williams needs to win Open to be No. 1

Here's one indication of how complicated the WTA's computer ranking system is: The WTA itself has a tough time figuring everything out.

A day after saying that Serena Williams could move past No. 1 Dinara Safina in the Sept. 21 rankings by reaching the U.S. Open final, the tour reversed itself Tuesday.

Instead, the tour clarified, Williams could rise from No. 2 a week after the tournament ends "if [and only if]" she were to win the U.S. Open.

There has been discussion and debate about the rankings lately, because Williams has won three of the past four major championships to raise her career total to 11, while Safina is still seeking her first Grand Slam title.

Safina lost in the third round at Flushing Meadows. Williams was to play in the quarterfinals Tuesday night.