By Clare Fallon
LONDON (Reuters) - Serena Williams, the Wimbledon winner in 2010, had a warning for Petra Kvitova, the present champion, ahead of the quarter-final meeting between the two at the All-England Club on Tuesday.
"I don't feel tired at all; I feel so fresh," the American sixth seed said after Monday's three-set win over Kazakh Yaroslava Shvedova.
"As time goes on and on, I tend to relax more and more and realize that this is a great opportunity for me."
A relaxed and fresh Williams could be bad news for Kvitova, who lost to the American in straight sets here in the semi-finals two years ago.
Kvitova, though, sees the match, the pick of Tuesday's women's quarter-finals, as a challenge.
"I think it will be a huge match for both of us," the Czech said. I am looking forward to playing against her, looking forward to having a challenge."
Weather permitting - and more rain is forecast after a day of disruption on Monday - world number two Victoria Azarenka will take on Austrian Tamira Paszek, the winner on Eastbourne's grass 10 days ago, for the right to play either Williams or Kvitova in the semi-finals.
In the top half of the draw, world number one Maria Sharapova's conqueror Sabine Lisicki takes on fellow German Angelique Kerber, the eighth seed.
Third-seeded Pole Agnieszka Radwanska, who, like Kerber, has yet to drop a set, plays Russian Maria Kirilenko.
While Tuesday should be strictly women's quarter-final day, the men may steal some of the thunder as only three of their scheduled fourth-round matches were completed on Monday due to the rain.
Organizers faced a logistical headache to squeeze in the five outstanding matches, with local hero Andy Murray due to start the day's action on Court One where he was leading Marin Cilic 7-5 3-1 when rain stopped play.
Former U.S. Open champion Juan Martin del Potro and Spanish seventh seed David Ferrer had been scheduled to play on Court One on Monday but will now kick off action on the main stage on day eight of the championships.
(Editing by Pritha Sarkar)
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