Federer was less than convincing against his Belgian opponent

The world number one eventually pulled off an unconvincing 6-7 7-6 7-6 win.

Federer, who lost the first-set tie-break 7-2, had to battle in the second before taking it 11-9.

Rochus went 4-2 up in the third set but Federer recovered to force a third and deciding tie-break, which he took 7-5 to secure the win.

The result left the three-times Wimbledon champion just two matches away from equalling Bjorn Borg's 41 consecutive wins on grass.

Fifth seed Tomas Berdych of the Czech Republic also reached the last four thanks to a 7-5 7-6 win over Frenchman Fabrice Santoro.

And Germany's sixth seed Tommy Haas also went through, beating Sweden's Robin Soderling 7-5 6-4.