Fish is the reigning champion in Houston

Fourth seed Fish levelled the match at one set all but then found himself two breaks down in the decider.

But he broke back twice to level the match and then broke again in the final game to clinch a 5-7 6-2 7-5 win.

"It was tough conditions out here today, and he's a very streaky player," said Fish.

"He plays very well when he's on and gives you some looks when he's not.

"He played well in the third set at the beginning and I picked up my game a little bit and I was lucky enough to win in the end."

Austria's Alex Peya was unable to make the most of his lucky loser opportunity as he lost 6-3 6-2 to Albert Montanes of Spain.