Roger Federer defeats Zverev for spot in ATP Finals semis

Roger Federer celebrates defeating Alexander Zverev on day three of the ATP Finals at the O2 Arena in London. (John Walton/AP)

LONDON — A day after the ATP Finals lost Rafael Nadal to injury, Roger Federer lifted spirits at the O2 Arena by extending his stay to the weekend.

The 19-time Grand Slam champion guaranteed his place in Saturday’s semifinals by defeating Alexander Zverev 7-6 (6), 5-7, 6-1 on Tuesday.

With Novak Djokovic and Andy Murray also absent due to injuries, the top-ranked Nadal’s withdrawal on Monday left Federer as the only member of men’s tennis’ ‘big-four’ in the tournament.

"It was nice to be able to show maybe that quality of mine, that I can dig out these matches, these points time and time again, stay mentally tough," Federer said. "In the third I started to play better. It was a tough match from the beginning till the end."

Zverev, who won his opening match against Marin Cilic, will face Jack Sock on Thursday to decide who will join Federer in the final four. Sock defeated Cilic in the early match, with Federer’s victory eliminating the Croat.

"It was a very positive match," Zverev said. "Obviously he won it. He’s in the semifinals. But even for me, I played the better match of the two today. I think I still have great chances of qualifying, playing Jack Sock next. I think if I continue having this level, I don’t know, maybe you’ll see me on the weekend still."

After an opening set dominated by serve went to a tiebreak, Federer came from 4-0 down and saved a set point to take the lead.

His grip on the match quickly tightened as a distracted Zverev made two double faults to gift a break in the opening game of the second set.

However, the 20-year-old regained his poise and took advantage of a dip in Federer’s first serve percentage to break back and then repeated the feat to force a deciding set.

From there on it was all Federer. The six-time champion, who is 16-years older than his opponent, showed his big-match experience as he regrouped to break in the third game, before doing so twice more to seal the victory.