LONDON, Nov. 16 -- Eighth seed Jack Sock upset world No. 3 Alexander Zverev to enter the last four of the ATP Finals at the O2 Arena here on Thursday.
Sock, who qualified for the season-ending finale for the first time by winning the Paris Master two weeks ago, took the first set 6-4 but suddenly disappeared in the second, losing it in only 28 minutes. The 25-year-old American was broken in the first game of the decider and received a point penalty for smashing a ball off the court.
But Sock, the first American to reach the final weekend of the season since Andy Roddick in 2007, broke back and regained the momentum, sealing the victory 6-4 as Zverev made too many unforced errors.
"That was a roller coaster match, for sure," said Sock, who finishes second in Group Boris Becker, behind group winner Roger Federer.
He will face Grigor Dimitrov, who won Group Pete Sampras, on Saturday.
Earlier, Federer won his third consecutive group match after fighting back from one set down to beat fifth seed Marin Cilic.
The second seed needed one hour and 54 minutes to win 6-7 (5), 6-4, 6-1 to finish Group Boris Becker play 3-0. It's the 10th time Federer has ended group play unbeaten.
The six-time ATP Finals champion thus extended his unbeaten run to 13 matches, including eight indoors, dating back to his Swiss Indoors Basel title run.
The 19-time Grand Slam champion will take on either David Goffin or Dominic Thiem from Group Pete Sampras, where Grigor Dimitrov has secured the first place.
"I played very well so really happy to be playing at this level right now," Federer said on court after his 55th ATP Finals win.
外研版高中英语选修11《Module 6 The Unitde Nations》（Listening and vocabulary）mp3听力
外研版高中英语选修11《Module 6 The Unitde Nations》（Words and expressions）mp3听力
外研版高中英语选修11《Module 4 Sherlock Holmes》（Reading practice）mp3听力
外研版高中英语选修11《Module 5 The Last Laugh》（Reading）mp3听力
外研版高中英语选修11《Module 7 Revision》（Reading）mp3听力
外研版高中英语选修11《Module 5 The Last Laugh》（Words and expressions）mp3听力
外研版高中英语选修11《Module 4 Sherlock Holmes》（Reading and Vocabulary）mp3听力
外研版高中英语选修11《Module 4 Sherlock Holmes》（Cultural corner）mp3听力
外研版高中英语选修11《Module 6 The Unitde Nations》（Reading and Vocabulary(2)）mp3听力
外研版高中英语选修11《Module 3 Ernest Hemingway》（Reading and speaking）mp3听力
外研版高中英语选修11《Module 5 The Last Laugh》（Reading practice）mp3听力
外研版高中英语选修11《Module 3 Ernest Hemingway》（Reading and Vocabulary(2)）mp3听力
外研版高中英语选修10《Module 6 The Maple Leaf Country》（Cultural Corner）mp3听力
外研版高中英语选修10《Module 6 The Maple Leaf Country》（Listening）mp3听力
外研版高中英语选修11《Module 4 Sherlock Holmes》（Words and expressions）mp3听力
外研版高中英语选修11《Module 5 The Last Laugh》（Reading and speaking）mp3听力
外研版高中英语选修11《Module 7 Revision》（Names and places）mp3听力
外研版高中英语选修6《Module 1 Small Talk》ppt课件之一
外研版高中英语选修10《Module 5 High-tech Living》（Reading and Vocabulary）mp3听力(1)
外研版高中英语选修11《Module 4 Sherlock Holmes》（Reading）mp3听力
外研版高中英语选修10《Module 5 High-tech Living》（Words and Expressions）mp3听力
外研版高中英语选修11《Module 7 Revision》（Listening）mp3听力
外研版高中英语选修10《Module 6 The Maple Leaf Country》（Reading Practice）mp3听力
外研版高中英语选修6《Module 6 War and Peace》ppt课件之二
外研版高中英语选修11《Module 5 The Last Laugh》（Listening and speaking）mp3听力
外研版高中英语选修10《Module 6 The Maple Leaf Country》（Reading and Speaking）mp3听力
外研版高中英语选修10《Module 6 The Maple Leaf Country》（Reading and Vocabulary）mp3听力(1)
外研版高中英语选修10《Module 5 High-tech Living》（Reading and Vocabulary）mp3听力(2)
外研版高中英语选修10《Module 5 High-tech Living》（Listening）mp3听力
外研版高中英语选修11《Module 4 Sherlock Holmes》（Listening）mp3听力