Andy Murray fought back from a set down to defeat Tomas Berdych at the Barclays ATP World Tour Finals.
With Novak Djokovic and Jo-Wilfried Tsonga also in his round-robin group at London's O2 Arena, defeat in his opening match would have left the US Open champion with an uphill task to qualify for the semi-finals.
And it did not look good when he dropped the opening set but he finally took a break point at the 11th time of asking early in the second and from there he kept Berdych at arm's length to win 3-6 6-3 6-4.
An improvement in Murray's serve had been crucial in the second set and that would need to continue for him to complete the comeback.
The sizeable crowd had been a little subdued but they roared when the Scot brought up two more break points in the third game of the decider, and again when Berdych put a forehand just wide.
Coach Ivan Lendl was back in Murray's box for the first time since the US Open and he would have been pleased with the way his charge had turned things around.
Berdych was beginning to look a little rattled but he dug in on his service games, although he was unable to make any headway on Murray's.
The 25-year-old has developed an unwelcome habit since the US Open of losing matches in which he has held match point, doing so in all three tournaments he has played following his New York triumph.
And he betrayed a few nerves with a double fault on his first chance here but on the second Berdych netted a backhand, leaving Murray to roar with delight as the fans acclaimed their man.