LOS ANGELES (Reuters) - Latvia's Ernests Gulbis survived a few anxious moments in the final set but held his nerve to upset top-seed Mardy Fish 5-7 6-4 6-4 and win the Los Angeles International on Sunday.

Serving for the match at 5-2, Gulbis was broken by American Fish and then trailed 30-40 on serve at 5-4 before sealing victory.

Gulbis, who had knocked out second seed Juan Martin del Potro of Argentina in the quarter-finals, pumped his right fist in celebration after becoming the first unseeded champion in Los Angeles since Radek Stepanek in 2007.

The triumph was Gulbis' first victory over a top 10 opponent this season. Fish fell to 6-13 in ATP World Tour Finals.

"I've played a lot of matches the past month and half, so he came in a little bit fresher than me. I think that played a part," Fish said.

"But credit to him. He played well when he needed to. He got those two breaks early, clearly which was big. I almost got him in the end... it wasn't meant to be." (Editing by Peter Rutherford; to query or comment on this story emailsportsfeedback@thomsonreuters.com)