World number two Federer, seeking a record-extending seventh title at the end-of-season finale, dished out yet more punishment to Ferrer in a 6-4 7-6 victory at the O2, taking his career record over the tenacious Spaniard to 14-0.
Ferrer is now vying with Juan Martin del Potro for the other semi-final spot from Group B after the towering Argentine thrashed Serbia’s Tipsarevic 6-0 6-4.
Tipsarevic, who pulled out of the Paris Masters last week after feeling unwell, has managed just eight games in four sets and cannot reach the semi-finals even if he beats Ferrer in his final round-robin match on Saturday.
Del Potro, beaten by Ferrer in his opener, will play Federer in his last group match.
Federer took a while to settle into his smooth rhythm against Ferrer who had numerous opportunities to make inroads in the opening games of their afternoon encounter.
Ferrer was 0-40 ahead on Federer’s opening service game but having failed to capitalise he was immediately broken himself.
He squandered more break points in the next game as Federer found himself 3-0 up without even playing well.
Ferrer, who has a season-leading 73 match wins this year, could have been forgiven for feeling pessimistic about his prospects but he was finally rewarded for his endeavour with a break in the fifth game when Federer wafted a backhand wide.