The second-seeded Russian lost a straight-set decision to No. 14 seed Venus Williams of the U.S., 7-6 (7-2) 6-1 in Thursday's semifinal on Centre Court.
Williams, a two-time Wimbledon champion, will face top-ranked Lindsay Davenport of the U.S. in Saturday's final.
The loss ended Sharapova's 22-match winning streak on grass, while Williams avenged her younger sister Serena's upset loss to the Russian in last year's final.
Venus Williams upset Maria Sharapova in Thursday's semifinal at Wimbledon. (AP Photo/Anja Niedringhaus)
"I've just been raising my form, and I love this tournament," said Williams, who hasn't won a Grand Slam for nearly four years. "This is the surface for me."
Rain held up Thursday's semifinals for over four hours before the bad weather subsided and play was able to get underway.
Davenport led Mauresmo 6-7 (5), 7-6 (4), 5-3, love-15 when another rain delay halted their match. The American needed just seven points Friday to complete her victory, beating Mauresmo 6-4 in the third set.
Venus's victory ensures at least one member of her family would play in the Wimbledon final for the sixth year in a row. Venus won in 2000 and 2001 and lost to her sister Serena in the final the next two years before Sharapova defeated Serena in 2004.
Williams squandered two set points on serve at 5-3 in the first set before easily winning the tiebreaker. She broke Sharapova at love to open the second set and then had to save a pair of break points in both the second and sixth games en route to the victory.
Williams overpowered Sharapova with some thunderous groundstrokes, breaking her serve four times, and finished with 23 winners compared to 13 for the Russian.
"I don't think I played my best tennis, but credit to her for not making me play my best," Sharapova said. "This tournament means a lot to me, more than any other tournament. I guess there are more years to come."
In the men's semifinals scheduled for Friday, top seed and two-time defending champion Roger Federer of Switzerland faces No. 3 seed Lleyton Hewitt, while No. 2 Andy Roddick of the U.S takes on No. 12 Thomas Johansson of Sweden.
Rain wreaked havoc with the tournament's schedule last year, disrupting play during the first week and completely washing out action for two days.
All the delays forced Wimbledon organizers to schedule matches for the middle Sunday – the traditional day of rest – for only the third time in the 128-year history of the tennis tournament.
with files from Associated Press
