Serena Williams is a Grand Slam champion again after crushing Maria Sharapova in the final of the Australian Open.

After two years spent largely in the wilderness, Williams clinched an eighth Grand Slam singles title - her third in Melbourne - with a majestic 6-1 6-2 win over the top seed to become the first unseeded champion since 1978.

Williams, who came into the tournament ranked a lowly 81 in the world, dominated from the outset and left her Russian opponent stunned.

Admittedly Sharapova was not at her best, but she wasn't allowed to be by Williams who appeared to have turned back the clock four years to a time when she dominated the game. When she won here for the first time in 2003, the former world number one became only the fifth woman in history to hold all four Grand Slam crowns at the same time.

Williams' big first serve was firing from the word go and she romped into a 5-0 lead.

Sharapova did get on the board in game six but Williams had no intention of surrendering her advantage and she clinched the first set in just 27 minutes.

The Russian, constantly being pushed back behind the baseline by Williams' powerful and precise groundstrokes, was broken in the opening game of the second set.

She had a chance to retrieve the situation immediately but an ace on break point from Williams saved it - it was to be Sharapova's second and final break chance. Neither was taken.

Soon Williams was serving for the title and, after two aces brought her to match point, it was all over when a backhand found its mark for Williams' 28th winner of the match. Sharapova made just 12, with the contest concluded in just 63 minutes.

A tearful Williams dedicated her victory to her sister Yetunde who was shot dead in 2003.

"I would like to dedicate my win to Yetunde. I love her so much," the 25-year-old said.

"I said a couple of days ago if I was going to win this it would be for her."

She added the victory was among the best of her career.

"This one is right up there with the top. Even I didn't expect to come in and win it all but you just always stay so positive.

"You always think, I'm going to win, I'm going to win. I still can't believe the tournament's over. I feel like there's another match to be played or there's something else. It's an awesome feeling."

Sharapova, who almost perversely will return to the world number one spot on Monday, praised her opponent.

"I've never underestimated her as an opponent," she told the Rod Laver Arena crowd.

"Not many of you here expected her to be in the final but I definitely did. She's an amazing champion - she's shown it here so many times.

"I look forward to playing her many more times and winning some I hope!"

Williams' renaissance is staggering given she played just four tournaments last year, a season dogged by injury.

She is now set to climb up to 14th when the WTA rankings are updated on Monday.