World number one Serena Williams advanced through to the fourth round of the Madrid Open this afternoon courtesy of a 7-6(5) 3-6 7-6(1) win over Victoria Azarenka.

Both players were commanding on their own serve throughout the first set, with neither able to even force a break point as the opener went to a tie-break.

Azarenka raced into a strong position by taking a 5-1 lead courtesy of two breaks, but the Belarusian then lost her next three points on serve to allow Williams a 7-5 victory.

The second set looked like going the way of the first as both players struggled to create break points in the opening stages, but Williams claimed the first of the match and took full advantage to take a 3-2 lead.

Azarenka hit straight back to level the scores with a break of her own, however, and backed that up with a second in succession on her way to a 6-3 victory to force a decider.

Williams broke early in the third set, but Azarenka's response to that setback was positive and she soon restored parity.

Service games were then traded until Williams had a match point in the 10th game, but she couldn't convert it, before she was broken in the very next game.

That left two-time Australian Open champion Azarenka to serve out for the match and it appeared that she was going to oblige at 40-0 to the good, only to then serve three double faults, sending the contest into a deciding breaker.

Azarenka appeared to be hampered by her failings during the previous game, which allowed Williams to ease to a 7-1 triumph.