Tomas Berdych felt just one point made the difference between winning and losing as he slipped to a 7-5 3-6 6-3 defeat to Kei Nishikori at the ATP World Tour Finals on Tuesday.
Sixth seed Berdych was involved in a keenly fought contest against his Japanese opponent and looked to be in the ascendancy when he fought back to level the match at one set all.
Berdych had an opportunity to break in the decider with the set locked at 3-3, but the Czech failed to convert his chance during a fierce rally and Nishikori forced him into a forehand error.
Nishikori went on to break in the next game and that proved decisive for the eighth seed to get his first win of the competition, having lost his opener to Novak Djokovic.
"I think it's been all about one point in the third set when I had the break point. The rally started pretty well for me, but I was not able to break him," Berdych said.
"Then I lost my serve. Basically, that was it. That was the difference. Everything was fine. I was playing a very good second set and I was playing well in the third.
"I was the one to have the first chance on break point in the third set. We had a good rally, I had a good position to finish the ball, but I didn't make it. Then he took the chance. He broke me in next game. That was it."
Berdych, who is now on the brink of elimination having lost his first two group matches, also stated that he is not entirely comfortable with the surface at London's O2 Arena, but refused to use that as an excuse for defeat.
"Honestly, I have never been a big fan of these courts particularly," he added. "But that's how it is. I just need to adjust to that. I just need to prepare as best as I can and try to play some good tennis.
"But, you know, it's the same for everybody. It just depends how the other guys are able to adapt and adjust their game on the court. That's kind of a big challenge for me, too."