Serena could knock defending champion Venus out of the competition on Wednesday.

When it comes to iconic sporting rivalries Serena Williams against Venus Williams should be right up there. It’s the first time in sporting history, two Afro-American sisters have become such icons worldwide in such an individual sport. However the rivalry has never really got going.

They have played each other twenty one times, eight of which have been grand slam finals. The head-to-head record is about as even as it can get (Serena leads 11-10)   However few if any of these encounters can be defined as classic matches and none have caught the public’s imagination. The last two Wimbledon finals sum this up, in 2008 Venus won 7-5, 6-4 and this year it was a straightforward 7-6, 6-3 win for Serena.

While Serena seems very much at the top of her game, Venus appears on the wane. Wimbledon aside, she’s achieved very little in the second half of the year and away from the lawns of SW19, her days as a title contender in the other three slams seem to be behind her.

Defeat today against Serena would knock her out after a dramatic three set defeat to Elena Dementieva on Tuesday.

Serena is 4/7 to win with bet365 but if you reckon Venus has some fight left in her, William Hill are offering odds of 5/4.