Federer came back in the second, taking it with the same 6-3 scoreline. And he was in full control in the decider, leaving his opponent no chance, 6-1.

“It means a lot to have returned to No. 1 and to finish the year again at No. 1. It was an incredible year for me both on the court and off the court and to be able to break the all-time Grand Slam record and finish the year on top is amazing,” Roger Federer told the tournament’s official website.

Federer leads Group A with two wins in two games, while Murray’s fate will be decided in his match against Fernando Verdasco.

The Spaniard likely wanted to save face at the season ending tournament, as his chances to progress to the semis faded after a three set loss to Juan Martin Del Potro.

Having lost their openers in London, both players knew a win was vital and both gave their best.

After taking a set apiece, it went down to the wire in the decider, where del Potro prevailed in the tie-break.

The Argentinean was ruthless, winning it 7-1 to give his chances to move into semis a big boost. The final score was 6-4, 3-6, 7-6.