Novak Djokovic maintained his winning run at the ATP Finals with victory over Daniil Medvedev in Turin.
Djokovic had already secured top spot in the Red Group but had to battle to earn a 6-3 6-7 7-6 victory in three hours 11 minutes.
Medvedev led 5-4 and was serving for the match in the decider before Djokovic recovered to take the set to a tie-break.
"It's a huge relief," Djokovic told Amazon Prime Video.
"Daniil and I had some battles in the past and I knew coming into the match today it's going to be his last match of the season, and he is definitely not going to want to finish the season with a loss.