Ljubicic also crashed out of the first round of the 2006 US Open

The Croat started well and took the first set but American Fish raised his game to secure a 4-6 7-6 (7-2) 6-4 6-4 victory in two hours and 53 minutes.

Ljubicic, who reached the last eight last year, went into the tournament in good form having beaten Andy Murray in the final of the Qatar Open.

"I was expecting a lot. I don't know who to blame except myself," he said.

"Mardy played very well, served very well. He was a tough opponent in the first round.

It was great to show everybody that I'm back Mardy Fish

"I believed until the last point that I had a chance but he kept coming up with great shots."

"Maybe I was putting too much pressure on myself. When I play ATP tournaments I feel like the world number four but maybe in Grand Slams I put myself under too much pressure."

Ljubicic did not appear to be feeling the strain when he took the opener with a single break in 41 minutes.

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But Fish, the world number 42, levelled the match as he raced through the breaker and then broke the Croat in the very first game of the third set to press home his advantage.

Ljubicic, cheered on by enthusiastic supporters, tried to respond but was immediately broken in the fourth set as Fish hit his groove.

"It was a great opportunity to play someone like him, to show everyone I can play, that I'm back," said Fish, who has been troubled by a long-term wrist injury.

"If everything clicked I knew anything could happen."

Amongst the other seeds to fall on day one were Argentine duo Jose Acasuso and Agustin Calleri, the 27th and 30th seeds.

American Zack Fleishman beat Calleri 7-5 4-6 6-3 6-4 while Samuel Querry, also from the United States, defeated Acasuso 6-7 (2-7) 6-4 6-1 6-3.