After falling to Serena Williams 6-1 6-3 in the Stanford quarterfinals, Maria Sharapova says that despite she and her foes accomplishments and high-profile names, that a real rivalry does not exist between the two.

"I think I’ll need to win a couple of more matches before it becomes a true rivalry," said the fifth-ranked Sharapova, who is now 2-7 against Serena and who hasn’t beaten her since 2004. "It’s not really a rivalry until I win few more matches. She’s experienced enough to know that even if it’s a small or big event you have to go out there and do our job and still go out there and win it."

Sharapova bested Williams twice in 2004, at Wimbledon and at the WTA Championships, but has now lost to her on six straight occasions and admittedly was sluggish in match that Serena had said she was itching to win. Sharapova came in the contest having won 17 of her last 19 matches, but at times looked mentally overwhelmed. She was remarkably unable to hold serve until the sixth game of the second set and ended the match with seven double faults.

"She goes for [returns] on first and second serves and that’s one of her strengths," Sharapova said. "She’s so powerful, she can stay really low and can rip it even if even it’s a good solid first serve… What really makes her dangerous is her ability to hit serves 120 and do that consistently. Of course she’s dangerous."

Serena was only playing the ninth match of her comeback but looked razor sharp.

"I’m better than I was month ago and I’ve put in a lot of work and I’m hoping it pays off because this is where I want to be," said Serena, who will face Sabine Lisicki in the semifinals.  "[The win] tells me I can compete in top the top 5. But I’m still climbing. It’s not a Grand Slam but it’s a great win for the hard court season and it is a big tournament."