The end-of-year action continued on Day 3 of the ATP Finals. These are the Top 5 photos from London, which concluded with a thrilling finish.
Roger Federer took care of business against Matteo Berrettini in his second round-robin match. The Swiss star posted a 7-6 (2), 6-3 victory to remain in contention with a 1-1 record.
Raven Klaasen and Michael Venus became the first team to clinch a semifinal berth after defeating Lukasz Kubot and Marcelo Melo, 6-3, 6-4.
Federer's fans quickly erased Sunday's disappointment, as the 38-year-old improved to 17-0 in second round-robin matches at the season finale.
Novak Djokovic, who was 3-0 against Dominic Thiem on hard courts, saw the tables turn when the Austrian prevailed in a final set tiebreaker to close out the night session.
"This was really one of these very special matches what I practice all my life for, what I practice all my childhood for," Thiem said after toppling the five-time champion to ensure his place in the final four.