Roger Federer saved two match points before edging past Belgian Olivier Rochus 6-7 7-6 7-6 to reach the semi-finals of the Halle International today.
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 tiebreak.
Rochus, who at 1.70 metres tall is one of the shortest players on the tour, twice came within a point of chalking up a memorable win after winning 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.
The result left the triple Wimbledon champion just two matches away from equalling Bjorn Borg's 41 consecutive wins on grass.