The world number seven was in almost constant control, combining fierce groundstrokes and ferocious returns of serve to win through to the semi-finals 6-3 6-4 in just 75 minutes.
Williams began in style by breaking Sharapova to love, but the American dropped her own serve in the next game when Sharapova hit a blistering return, and then double-faulted to fall behind 4-2.
Most of the games in the second set were closely contested, the players swapped breaks in the third and fourth games, before Sharapova struck a fierce forehand that forced a backhand error and gave her a further break for 4-3.
"I was able to pick up my game when I needed to and force her to make some unforced errors," Sharapova said. "I thought I was dictating the match throughout and I'm definitely playing with a lot of confidence."
It was her 11th victory in a row, following on from tournament triumphs in Seoul and Tokyo, and countrywoman Elena Dementieva now lies in wait after the third seed overcame Ai Sugiyama of Japan.
Ninth seeded Sugiyama earned just one point on her own serve as Dementieva dominated the opening set, but almost every game was then keenly contested.
Sugiyama's persistence in the rallies counteracted the power of Dementieva's groundstrokes, but the Russian's infamous weak serve once more proved costly when she double-faulted a fourth time to drop the second set.
Both players had their chances to take control of the deciding set but it was the Russian who broke for a second time to take a 6-5 lead, and she made no mistake serving out for a 6-1 5-7 7-5 success.
The second semi-final will be between 10th seeded Patty Schnyder of Switzerland and unseeded Australian Alicia Molik.
Former champion Schnyder defeated Argentina's Paola Suarez 2-6 6-3 6-4, and Molik overpowered eighth-seeded Russian Nadia Petrova 6-3 6-1.
