Serena Williams recovers to beat Victoria Azarenka, sets up Maria Sharapova semi

The American, who will face Russia's Maria Sharapova in the semi-finals, is two wins away from holding all four grand slam titles concurrently -- the so-called Serena Slam she also achieved in 2002-03.

Williams and Azarenka have history, although not in any sinister sense. Both are fierce fighters and have contested some intense battles down the years, including two U.S. Open finals.

Former world number one Azarenka, seeded 23 but far more dangerous than that in reality, outplayed her opponent in a superb first set, absorbing the power of the Williams arsenal and punching back some spectacular winners.

When she sealed the first set with a clean-as-a-whistle forehand pass a fourth career win from 20 matches against Williams looked not only possible, but likely.

Azarenka was fired-up and raising the decibel level.

But then came the retaliation.

Williams, who narrowly escaped defeat by Briton Heather Watson in the third round on Friday, added a few clicks to her serve, beefed up her forehand and began bellowing "c'mons!" after winning big points.

Azarenka was taking some fearful punishment but somehow survived a Williams onslaught in an 18-point game at 1-2, saving three break points to level at 2-2.

The Belarussian had a break point in the next game but Williams responded with a backhand winner, held serve, and then won the next three games to level the match.

Sensing another semi-final, Williams marched ahead in the decider, banged down three consecutive aces to move 5-2 ahead and finished Azarenka off with three more in the final game.