The Swiss star had already secured a place in the semi-finals after winning his opening matches against Germany's Alexander Zverev and American Jack Sock.

Cilic had suffered defeat to both opponents to rule him out of contention for the last four, but proved a strong resistance today.

The Croatian fended off break points in his first service game and took the opening set to a tie break.

He ultimately edged Federer to raise the prospect of a surprise result against his Swiss opponent, whom he had lost to in this year’s Wimbledon final.

Federer hit back by breaking in the second set, with the 36-year-old seizing the momentum to take the tie into a decider.

The six-time winner dominated throughout the third set to wrap up a 6-7, 6-4, 6-1 victory.

"I think Marin served well and was a bit better in the breaker,” said Federer.

“I was in trouble a set and a break point down in the second set.

“I'm happy I found a way out of it and in the end, I played really well."

Zverev and Sock met in the final match in the Boris Becker group, with the winner advancing to the semi-finals.

It was the American player who made the better start, with Sock edging the opening set 6-4.

The momentum shifted considerably in the second, as Zverev stormed back by winning the set 6-1 to force a decider.

The German immediately broke to appear on course for the semi-finals, with Sock then given a penalty point after firing a ball into the crowd in frustration.

It appeared to have an affect on the 25-year-old, who won the Paris Masters to reach the finals, as he immediately secured two breaks to edge in front.

While Zverev once again levelled the scores, the German double faulted to give Sock a match point, which the American took to seal a 6-4, 1-6, 6-4 win.

The winner of the Pete Sampras group tie between Dominic Thiem of Austria and Belgium’s David Goffin tomorrow will reach the semi-finals.

They will take on Federer, while Sock will meet Bulgaria’s Grigor Dmitrov, who secured his spot after winning his second group match yesterday.

He will go in search of a third straight victory when he takes on Spain’s Pablo Carreno Busta.

Busta replaced his compatriot Rafael Nadal after the first match of the season ending event, with the world number one having withdrawn through injury.