Serena fights back to win

Serena Williams stormed back from the brink of defeat to keep her hopes of defending her Australian Open title alive with a 4-6 7-6 (7/4) 6-2 win against Victoria Azarenka.

The world number one looked set to suffer a shock quarter-final exit when she trailed 4-0 in the second set, having already conceded the first.

The 28-year-old then rallied impressively to reel off the next five games before winning the set in a tie-break.

It served to break the resolve of the Azarenka, whose earlier heavy hitting was replaced with timid groundstroke in the deciding set to allow Williams to overpower her and book a last-four meeting with China's Li Na.

Williams has won the tournament on each of the previous four occasions she has reached the semi-finals.

After the match Williams admitted she thought she may be getting an early flight home.

Asked what was going through her mind at 4-0 down in the second set, Williams replied: "I was actually thinking 'If I lose today and I lose in doubles I think I can catch a flight on Friday'. That's not what a champion is supposed to think, but that's what I was thinking. I'm just happy to still be here."

Williams had not lost a single service game in the tournament but was broken in four of her opening seven service games as the seventh-seeded Belorussian stole away for what looked like a match-winning lead.

Williams' serve slowly improved, however, and she started to match Azarenka's heavy hitting to drag herself back into the contest. The set went to a tie-break and Azarenka opened an early 3-1 lead to move within touching distance of the win. But again Williams rallied winning six of the next seven points to take the set.

The decider was all one-way traffic as Williams served confidently to overpower Azarenka and deny the Belorussian her first ever grand slam semi-final appearance.