Venus Williams (13/2 2010 Australian Open – Women’s Outright) has admitted she will have to raise her game to find a way past top-seeded sibling Serena in a possible semi-finals clash at the Australian Open.

The American sixth seed, who dropped the first set before prevailing 3-6 6-2 6-1 against Francesca Schiavone on Monday, must first find a way past in-form Na Li, who crushed number four seed Caroline Wozniacki in straight sets, in the last eight.

The five-time Wimbledon winner (11/4 second favourite Women’s Wimbledon 2010 Outright) and two-time US Open champion admitted Schiavone had made her work for a place in the quarter-finals and was relieved to get through.

She remains on course for a semi-final blockbuster against sister and defending champion Serena, but knows her game must improve.

When asked what she could do to defeat Serena, who has won the past four matches between the pair, Venus replied: “Play better.

“I think it’s challenging because we’re both so good. We both want to win.”