By Sarah Holt
BBC Sport at Wimbledon
Venus Williams ended Maria Sharapova's title defence and booked her own place in the final with a 7-6 (7-2) 6-1 win.
Williams broke first to take a 4-2 lead in a gripping opener but Sharapova responded with some fine groundstrokes to break back and force the tie-break.
The two-time champion raced 3-0 ahead as Sharapova mistimed her shots and went on to win a fantastic first set.
Sharapova gifted Williams a break at 1-0 in the second, and the American broke twice more to roar to the final.
Williams will either face Amelie Mauresmo or Lindsay Davenport for the title after the other semi-final was suspended because of rain.
Sharapova had bettered Williams in their two previous head-to-heads and forced the American to fight off two break-points in the very first game.
But the Russian immediately came under pressure on her own service game, clawing back from 0-40 to hold at 1-1.
Williams' power and depth were met by Sharapova's own determined groundstrokes from the baseline but, after a fierce rally, Williams took the first break.
The former Wimbledon champion looked to have the first set well within her grasp and held two set-points at 5-4.
But she failed to convert them and her Russian opponent pounced to break back as Williams sent her forehand long.
Both players ground their way to the inevitable tie-breaker, their groans growing as they forced one another to chase the ball across Centre Court.
A lapse of concentration from Sharapova saw Williams race ahead, and she comfortably closed it out to take the set.
The Russian teenager looked a little shell-shocked as she opened up the second.
A string of unforced errors saw her lose her first game to love, and this time Williams made no mistake, consolidating the break at 2-0.
The American 25-year-old was back to her best, breaking again at 4-1 in the face of a wilting Sharapova.
As the clouds began to darken over Centre Court, Williams surged on despite Sharapova's last efforts, ensuring a Williams sister was in the Wimbledon final for a sixth straight year.
"Serena sent me an email telling me if I stayed in there and played my game then I was the best," Williams told BBC Sport. "And I remembered what she told me.
"I love this tournament, this is the surface for me and I have a good record here, so it's all kind of fallen into step.
"My aim in the tournament is just to be as good as I could in each round but my level has raised with each match."
A subdued Sharapova conceded after the match she had lost to the better player in a rain-delayed semi-final.
"I played against a really good opponent and today it went to the better person," she said.
"I don't think I played my best tennis but credit to her for not making me play my best. She had a lot of hard, deep balls and was serving consistently big.
"I'm very sad as this tournament means a lot to me, more than any other tournament but there are many more years to come and I will do everything I can to come back and win."