Rafael Nadal [Images] dug deep into his reserves to extend his winning streak on clay to 45 matches on Friday with a 4-6, 6-4, 6-3 win over Finn Jarkko Nieminen in the quarter-finals of the Barcelona Open.

The defending champion and top seed battled back from 4-6, 1-4 down to set up a semi-final against unseeded Spaniard Nicolas Almagro, who upset 10th seed Juan Carlos Ferrero 6-3, 6-3.

If Nadal wins the title, he will overtake second-placed Bjorn Borg in the open-era list of most consecutive wins on the surface. Argentine Guillermo Vilas owns the record with 53.

"It was a really difficult match," Nadal said.

"It was really hard in the second set but I was always thinking about victory. From 1-4 if I could have five good games I could win."

For a set and a half, it looked as though Nadal's incredible run was about to end as Nieminen played inspired tennis.

Taking the attack to the Spaniard, the Finn fired a succession of winners while at the other end, Nadal made an uncharacteristically high number of mistakes.

The 19-year-old somehow found another level to win five consecutive games from 4-1 down to level the match.

He again broke in the first and final games of the deciding set to clinch victory, which he celebrated as if he had won the title.

Ferrero, the 2003 French Open champion, had been expected to come through to face Nadal in the semi-final but Almagro was too consistent.

Sixth seed Tommy Robredo of Spain will play unseeded Swiss Stanislas Wawrinka in the second semi-final.

Robredo, who earlier finished off his rain-delayed third-round match with Spaniard Fernando Verdasco 6-3, 2-6, 6-2, followed it up by beating Czech fourth seed Radek Stepanek 6-3, 6-2.

Wawrinka beat unseeded Ivo Karlovic 4-6, 6-3, 6-4, becoming the first man to break the Croatian's serve this week.

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