Federer fights back to reach final

The Swiss, bidding to complete his haul of the grand slams, recovered from a slow start to claim a 3-6 7-6 (7/2) 2-6 6-1 6-4 victory in three hours and 28 minutes.

The second seed will meet Robin Soderling in Sunday's final after the Swede defeated Fernando Gonzalez 6-3 7-5 5-7 4-6 6-4 earlier on Friday in another thrilling five-setter to continue his remarkable run in Paris.

It was Federer's second five-set win this tournament - he was also taken the distance by Tommy Haas in the fourth round - and he has squeezed through to his fourth straight final here without being on top form.

When Federer, 27, lost the third set to Del Potro, the Argentinian was serving consistently and his powerful groundstrokes were proving too much for the world number two.

By that stage, Federer had only earned two break points, converting neither of them, but he turned that around to finish the stronger.

He is now just one win away from becoming the sixth player to complete a sweep of the Majors. The title here would also move him level with Pete Sampras on a record 14 grand-slam crowns.

Earlier, Soderling came from 4-1 down in the final set to see off 12th seed Gonzalez in a riveting battle of the big hitters.

Soderling, the conqueror of reigning champion Rafael Nadal in the fourth round, continued his sensational run at Roland Garros by posting a five-set victory over the Chilean powerhouse in an epic match that, bizarrely, also lasted three hours and 28 minutes.

The 23rd seed reaches his first grand-slam final, where he will bid to deny Federer the French Open title he so desperately craves.