Big-serving American John Isner has revealed that he is suffering from the weight of expectation after making a shock first-round exit from Wimbledon.

The 27-year-old was beaten in five sets by Colombia's Alejandro Falla, despite having a match point in the fourth-set tie-breaker.

Isner, who has climbed to number nine in the world rankings, said that he is feeling the pressure on court.

"I'm just really down on myself right now," said Isner. "I'm trying not to feel the outside pressure. There are some good things expected of me, and I'm glad I'm in that position, but I'm just not performing right now. It's just ugly right now.

"Sometimes, and lately it has been happening quite a lot, I get out there in the match and I'm just so clouded. I just can't seem to figure things out. I'm my own worst enemy out there. It's all mental for me, and it's pretty poor on my part.

"I didn't put my opponent away. I had my chances, and I didn't do it. It's all on me."

Falla will now play the winner between Paolo Lorenzi and Nicolas Mahut in round two.