Agassi is playing his first tournament since last November

Agassi, 35, took a 4-2 lead in the first set but eventually lost it before saving two match points on his serve in the 10th game of the second set.

"In the second set he was all over me," he said.

"The match could have gone either way. If I'd hit one shot wrong, he could've won it."

He added: "To a certain degree you have to ignore the score and make the guy execute."

Agassi will play Guillemo Garcia-Lopez of Spain in the next round.