Williams’ last Grand Slam final appearance came at the All England Club two years ago, finishing runner-up again to her younger sister, Serena.

A stomach muscle injury then saw the 25-year-old out of action for around six months, and she struggled to recapture the form which had taken her to the top of the world rankings since, a quarter-final appearance at the French Open in 2004 her best performance before this summer.

However, this evening – in a match which did not start until 5.39pm, following intermittent showers all afternoon at SW19 – the American signalled she is anything but a spent force.

Because of the bad weather, the match had been been moved forwards after the other last-four encounter was switched to Court One.

And it was Williams, controversially seeded only 14 by the AELTC, who started brightly.

After saving two break points on her opening serve, the American had too much power for the defending champion in the next game, moving 40-love ahead.

Sharapova, though, recovered to deuce and then advantage twice, before a forehand into the net from Williams gave her the game.

The set then went with serve as both players seemed happy to slug it out from the baseline, until game six when Williams forced two break-point chances with some more stunning passing shots.

And she moved 4-2 ahead when her 18-year-old opponent eventually netted a forehand following another tense rally from the backcourt.

Sharapova – who beat the younger Williams sister, Serena, in last year’s final - then saved two set points against her, at 3-5 down, before eventually breaking back when the world number 16 fired a forehand long.

With tensions high, the set then moved to a tie-break after both women managed to hold serve.

Sharapova then found herself 3-0 down after twice hitting forehand just wide, that was soon 5-2, and Williams served out to secure the first set in one hour and two minutes.

It was the first set Sharpova had dropped during this year’s championships, with Williams producing the type of power game which saw her dominate the sport at the turn of the century.

The 25-year-old American former world number one forced an early break in the opening game of the second set – keeping the pressure on the defending champion, who again produced too many unforced errors.

Williams, however, then immediately faced the prospect of losing her own erve, before eventually the Russian sent another rash return well wide from the baseline to leave herself two games down.

Both players then held serve until game five, when Sharapova’s backhand return hit the net cord and dropped back, to move Williams 4-1 ahead as the skies over SW19 darkened.

The Russian then managed to force a break-point chance of her own in the next game, but sent an attempted pass long after Williams came to the net.

Sharapova botched a drop-shot to give the American an advantage, which she did not take before then firing a double-handed back-hand well long to give the Russian another break chance.

The champion, though, failed to capitalise and let Williams gain the upper hand again, as she eventually held serve and moved within one game of the Wimbledon final.

A double-fault from Sharapova levelled game seven at 30-all, before a fine passing shot down the right gave Williams match point.

The American came to the net, the whole court at her mercy, but blazed the ball long.

Another wayward return allowed Sharapova advantage, before another double fault returned the score to deuce.

With light drizzle now falling on Centre Court, the Russian wasted another advantage before a wide forehand gave Williams a second match point.

Sharapova went for a cross-court winner, but was again just out of range, to give the American an unexpected, but thoroughly deserved straight-sets victory.