The American became only the second unseeded woman to win the Australian Open crown in the professional era after Chris O'Neill achieved the feat in 1978.

Williams unleashed a barrage of winners throughout the match and set the tone for what was to come when she broke Sharapova in her first service game and completely overwhelmed the world number one elect to seal victory in 63 minutes and claim her eighth grand slam title.

Williams, twice former champion but unseeded due to injury problems last year, clinched the first set in 26 minutes when Sharapova sent a backhand wide.

Williams broke serve again in the opening game of the second set and romped through it to win her third Australian Open title.