Roger Federer has quailified for the semi-finals of the ATP World Tour Finals as he maintained up his perfect career record against David Ferrer with a straight sets win.
Federer improved to 14-0 against the Spaniard as he ground out a 6-4 7-6 (7/5) victory at the O2 Arena in London.
He did not have things all his own way against Ferrer, who defeated Juan Martin del Potro in his opening match, but came through in an hour and 49 minutes to stay on course to defend his title at the event.
Ferrer headed into the clash on an 11-match winning streak following his triumph at the Paris Masters last week but, having managed only three sets in his previous meetings with Federer, made a poor start as his Swiss rival broke en route to an early 3-0 lead.
But that did not tell the whole story as the world number two was forced to fend off six break points in doing so and they were back level after Ferrer finally took his eighth chance.
As so often, though, Federer moved up a gear just when he needed to and, with his opponent serving to stay in the first set at 4-5, he emphatically broke to love to take control of the contest.
Ferrer had further opportunities at the start of the second set but once again could not take them, Federer saving two more break points.
The set remained tight throughout and Ferrer stayed with his opponent all the way until an inevitable tie-break, but once there an error on the sixth point proved crucial.
Federer had been immaculate on serve and took his third match point when a Ferrer return dropped long to become the first singles player through to the last four.