LONDON: David Goffin survived a shaky start to his ATP Finals shootout against good friend Dominic Thiem on Friday to win 6-4, 6-1 and advance to the semi-finals, where he has the daunting task of taking on Roger Federer. The Belgian seventh seed lost the first three games against Austria’s Thiem at London’s O2 Arena but roared back to win six of the next seven and take the set. After Thiem received medical treatment for an apparent cut on his left knee, Goffin established an iron grip on the match with an early break in the second set as his fourth-seeded opponent continued to struggle to land first serves. Goffin, who beat Rafael Nadal in his round-robin opener in the Pete Sampras group, showed impressive mental strength to bounce back from his poor start to the match after losing heavily to Dimitrov. Federer, chasing a seventh end-of-season trophy, topped the Boris Becker group with American Sock in second place.Sock will play Bulgaria’s Dimitrov in Saturday’s other semi-final after he booked a place in the semi-finals with a surprise 6-4, 1-6, 6-4 win over German prodigy Alexander Zverev on Thursday night. Sock is the first American to reach the semi-finals of the season-ending event since Andy Roddick in 2007.The 25-year-old, up to a career high ninth in the world rankings, only qualified for the Tour Finals thanks to his first Masters title in Paris earlier this month. 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. “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.
