Williams survives battle

The match lurched in fortunes continuously on the way to becoming the longest women's semi-final in the Open era at two hours and 49 minutes.

Williams's victory set up a fourth all-Williams final at the All England Club, after Serena's sister Venus thrashed world number one Dinara Safina 6-1 6-0 in the other semi-final.

After a low-key women's tournament to-date, the thrilling clash was played in energy-sapping conditions on Centre Court, with temperatures soaring to 34 degrees.

The opening two games saw both serves broken with neither player able to settle or find sufficient rhythm, but from then on the contest was of the highest quality.

Dementieva won the first set, having seized control of the tie break to win it 7-4 after 12 cagey games, with both players battling hard to gain the ascendency.

Williams hit back to take the second set, an incredibly tense affair in which two breaks of serve were exchanged before the crucial advantage was taken by the American in the 11th game.

Under intense pressure the twice Wimbledon champion closed out the set to level the match after Dementieva had squandered numerous opportunities to hit back.

The Russian edged closer to victory with a crucial break of serve in the fourth game of the deciding set, but she then imploded under the scrutiny of her opponent's advances, and Williams broke straight back in the following game.

Williams held her nerve impressively with a crisp volley to save a match point at 5-4 down, and the American battled her way through a gutsy service hold.

The final set was finely poised throughout, and it took until the 13th game for Williams to finally make the crucial breakthrough.

Having capitulated on her serve, Dementieva had nothing left to give as Williams stepped in to close the match out.

The American held her composure superbly in the final game with a controlled service hold, which prompted a shriek of delight from her at its conclusion.

Given Venus's serene progress in her semi-final, conceding just one game, the onus will be on Serena to recover her energy for Saturday's showpiece match.