Roger Federer secured his place in the semi-finals of the ATP World Tour Finals by beating Kevin Anderson 6-4, 6-3 at London's O2 Arena.
It is the 15th time he has reached this stage of the competition.
Federer and Anderson exchanged breaks towards the end of the first set, with the Swiss breaking twice to love to take a 5-4 lead.
He sealed his place in the semi-finals when he held to take the opening set 6-4, besting Dominic Thiem on games percentage.
And after his disastrous straight-sets loss to Kei Nishikori on Sunday, Federer still finished top of the group when he concluded a straight-sets win over Anderson to add to his win over Thiem, securing two breaks in the second set to wrap up a 6-4, 6-3 victory.
"I'm very happy," said Federer afterwards. "I tried to come up with a good game plan against Dominic and Kevin...it's been a fun group."