LONDON: Jack Sock became the first American to reach the last four of the ATP Finals for 10 years when he stunned world number three Alexander Zverev in a firecracker of a match on Thursday.

The world number nine, the first American to reach the final weekend at the season-ending tournament since Andy Roddick in 2007, triumphed 6-4 1-6 6-4 to prolong his London adventure.

“I didn’t expect to be in London in the first place,” said Sock, who qualified only this month after winning the Paris Masters. “Paris was a big step for me. Now to put myself in the position to play on the weekend is another big step forward, another confidence-booster.”

Sock was so sure he wouldn’t make it to the O2 Arena that he had planned to play a round of golf at Augusta this week.

Instead of working on his putting, Sock ground out a hard-fought victory over third seed Zverev, securing second place behind Roger Federer in the Boris Becker group and a Saturday semi-final date with Pete Sampras group winner Grigor Dimitrov.

“That was a rollercoaster match. I didn’t have the hottest start in the third but I kept in there and kept fighting,” Sock said.

Sock again played an entertaining match, complete with another ‘tweener and even a point penalty for smashing a ball into the crowd.

But it was a pair of errors from Zverev in the final game that gave Sock the match. Trailing 5-4 and at 30-all, Zverev double-faulted for the eighth time to hand Sock a match point. The 20-year-old German then put a forehand wide to end it.

“Yeah, I choked,” Zverev said. “It’s quite easy. Won the second set 6-1. I was 1-0 with a break. He got a point penalty. I was down 1-4 within 10 minutes where I didn’t put many balls in the court.”

Six-time champion Federer had already won the Boris Becker group, having battled back to beat Marin Cilic earlier to post a perfect round-robin record at the event for a 10th time.

Just four months ago and only a few miles across south London, Federer was celebrating his record eighth Wimbledon crown after crushing Cilic in a brutally one-sided final.

Cilic had been hampered by a blistered foot and the Croat was reduced to tears during the match as his predicament sunk in.

In their first meeting since that All England Club showdown, Federer frustrated the already eliminated Cilic once again as he fought back to win 6-7 (5-7), 6-4, 6-1.

“It wasn’t easy,” Federer said. “I mean, look, it’s a fast court. It’s indoors. We’ve seen it now: When you miss a few too many opportunities you can really pay the price at this tournament.”

Published in Dawn, November 18th, 2017