Federer Faces Early ATP Finals Exit After Thiem Defeat, Djokovic Cruises

Roger Federer said he had no more margin for error if he wanted to avoid an early exit at the ATP Finals after losing his opening group match to Dominic Thiem on Sunday.

The 38-year-old Swiss, bidding for his seventh title at the event but his first since 2011, struggled to handle Thiem's aggressive game as he went down 7-5 7-5.

Only once in 16 previous appearances has Federer failed to survive the group phase, in 2008, and to avoid a repeat he will have to beat Italian Matteo Berrettini on Tuesday and most probably Novak Djokovic on Thursday.