After dropping the first set, Nadal’s feted determination looked set to overcome his unusually high error count as he battled back to win the second set before claiming a double break in the decider to go 3-0 ahead.

But the Spaniard never looked comfortable on court and meekly dropped the next four games to rejuvenate Del Potro’s challenge.

The Argentinan, however, was not enjoying his best day on court either – ironic given he would record his first win against a top-four opponent – and nervously passed up three match-point opportunities at 6-5.

Nadal held to take the match to a deciding tie-breaker where he got his nose ahead at 3-2 with a mini-break.

But the Mallorcan again lost his way, although this time it was more to do with a couple of cracking cross-court backhands from Del Potro, who reeled off five straight points to clinch the match.

Perhaps fittingly, the Argentinan’s win was sealed when Nadal dumped a forehand into the net and send Del Potro through to the last four of a Masters Series event for the first time.

Del Potro will meet third seed Andy Murray in the last four after he cruised past Fernando Verdasco 6-1 6-2 in just 75 minutes.

Verdasco had beaten the Scot in five sets when they last met at the Australian Open in January, but there would be no repeat of the closeness of that match.

Like he did in the previous round against Viktor Troicki, Murray immediately claimed two breaks of serve to race into a 4-0 lead after just 15 minutes on court.

Verdasco did break back to love in the next game, but Murray’s cushion was immediately restored – the Spaniard racking up errors as he sought to go for his shots.

Murray was happy to retrieve balls and in the windy conditions it proved the smarter tactic as Verdasco continually missed the lines.

Murray served out the set with Verdasco taking a three-minute medical break at the change to allow the trainer to work on a hamstring complaint.

When he returned he again lost his opening two service games to effectively end his hopes as Murray cruised through to the last four.

In the women’s event, Victoria Azarenka ensured she will play the biggest match of her career on Saturday after beating Svetlana Kuznetsova 6-3 2-6 7-5 in their semi-final.

The 19-year-old from Belarus is enjoying by far the best season of her career, winning her first two titles – in Brisbane and Memphis – while she also reached the semi-finals in Indian Wells last week.

Eleventh seed Azarenka got the better of five breaks of serve in the opening set.

But eighth seed Kuznetsova hit back in the second, breaking Azarenka three times to level.

The deciding set was much tighter with Azarenka successfully defending an early break to move to the brink of victory.

But she faltered while serving for the match allowing Kuznetsova, who had won their three previous meetings, to break back.

However, Azarenka responded straight away by breaking again and this time she held firm to seal her spot in the final.