Roger Federer [Images] saved four match points before edging past Belgian Olivier Rochus 6-7, 7-6, 7-6 to reach the semi-finals of the Halle International in Halle, on Friday.

The Swiss world number one, unbeaten on grass since losing to Mario Ancic in the first round of Wimbledon in 2002, was given a real fright in the second set.

Rochus, who at 1.70 metres tall is one of the shortest players on the tour, three times came within a point in the tiebreak of chalking up a memorable win, after earlier holding another match point at 6-5.

Rochus had won the first set tiebreak 7-2.

After staving off the danger, Federer took the tiebreak 11-9 on his third set point to level the match after one hour and 51 minutes.

Rochus refused to wilt under pressure and went 4-2 up in the third until Federer finally produced the goods to keep alive his hopes of a fourth successive title here by winning the tiebreak 7-5 on his sixth match point. The result left the triple Wimbledon champion just two matches away from equalling Bjorn Borg's 41 consecutive wins on grass.

He will next play Germany's [Images] Tommy Haas or Robin Soderling of Sweden.

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