World number one Novak Djokovic believes that his defeat in the final of Wimbledon was partly down to his demanding semi-final clash against Juan Martin del Potro.
"I cannot look for excuses but the previous match took a lot out of me," Djokovic told reporters.
"I've been in these situations before. I felt okay but maybe physically I didn't have enough gas in the important moments.
"It was a very long match for three sets today. But the bottom line is that he was a better player in the decisive moments."
Djokovic has won six Grand Slam titles in his career so far.