Wawrinka says he ran out steam against nervous Djokovic NEW YORK (Reuters) - Defeated U.S. Open semi-finalist Stanislas Wawrinka was moved by the support he received from a packed Arthur Ashe Stadium on Saturday but simply ran out of steam in a five-set loss to top seed Novak Djokovic. "Unfortunately I struggled a little bit physically," Wawrinka told reporters after an enthralling 2-6 7-6 (4) 3-6 6-3 6-4 battle with Djokovic. I think that this was completely different match than the (fourth round) match we played in the Australian Open. In the Australian Open I had to play my best game to stay with him. Wawrinka took a medical break in the fourth set to have his thigh taped and twice in the latter stages the Swiss grabbed brief pauses in play, sitting on the advertising boards. "Today I had the feeling when I was still fit, when I was still healthy I had the match in control," said the ninth seeded Wawrinka. I think I was playing better than him. But he's not number one for nothing. He was staying with me all the match, and at the end he pushed me, pushed me far, far, far back. I had to find everything I had in my body today to stay with him, and he won the match. Wawrinka, playing his first grand slam semi-final, said he knew that fitness was going to hamper him as early as the third set. "At the end of the third set I started to feel my right leg, and at that moment I knew I was going to be out of fuel if I had to play a long match and struggle a little bit against him, especially against him because he's such a good defender," he said. I had to change a little bit my game because I couldn't be that aggressive. Wawrinka's inspiring effort, particularly a remarkable 21 minute third game in the fifth set, drew rich appreciation from the New York crowd who stood in applause for the 28-year-old and interrupted his post-match on court interview with cheers. It was a great feeling, that's for sure. I enjoyed it a lot," said Wawrinka. That's why you play tennis - to play in front of people like today in the biggest stadium in tennis. Even if I lost today, I was still happy to hear all the cheering and to hear all the crowd like this. I think it's something quite amazing for me. While Wawrinka inevitably spoke about taking the positives out of the best slam performance of his career, he hinted at some disappointment he didn't make more of the Serb's shaky start. "I think he was much more nervous than normal," said Wawrinka, assessing his opponent. Usually I play him in the fourth round, something like that, and today he knew that it was going to be a tough match because I was playing well since the beginning of the tournament. I had the feeling that he was really, really nervous and struggling to find the plan and struggling to find the game how to beat me. Reporting By Simon Evans, editing by Steve Keating