Serena Williams has clinched her sixth Australian Open title with a straight-sets victory over Maria Sharapova.

The world number one was pushed all the way by the Russian, but she prevailed by a 6-3 7-6(5) scoreline in one hour 51 minutes.

Williams went into the match still suffering from the illness that has affected her throughout the tournament in Melbourne, but with a 15-match winning streak against the second seed, she could feel confident of securing another Grand Slam title.

The signs were ominous for Sharapova early on as she immediately fell a break behind, and that's how it remained until midway through the sixth game when the two players were forced off court due to rain.

After the roof was initialised, Williams returned to capture the second break, and although Sharapova hit straight back, the 33-year-old struck for a third time to move one set away from the title.

The second went much of the way of Williams, but Sharapova, who won in Australia in 2008, wasn't prepared to back down as she saved break points in the second, fourth and eighth games before driving a forehand winner into the corner to save championship point at 5-4 down.

Despite being behind for much of the set, Sharapova was full of belief heading into the tie-break and she secured the mini-break on the opening point, but by the change of ends, Williams had hit back to lead 4-2.

Sharapova saved a second match point at 6-4 down after another forehand winner, but Williams finally sealed victory, and her 19th Grand Slam title, with an ace out wide.