Andy Murray came from a set down to book his place in the quarter-finals of the Cincinnati Masters on Thursday.

Murray dropped the opening set to Latvia's Ernests Gulbis and had to save three break points early in the second. But the world number four finally found his touch to break Gulbis in the sixth game before winning his next two service games to love to level the match.

The decider began with the players exchanging breaks of serve, with Murray again crucially saving break points to keep in touch. The Scot then powered through the subsequent tie-break, moving into a 6-1 lead before taking it 7-4 to complete a 4-6 6-3 7-6 (7/4) victory.

"The conditions were very warm, I was struggling a little bit early on to control the ball and he was hitting huge and making it very difficult," Murray said.

"(In the tie-break) he is comfortable when he's dictating the points and I wasn't going for too much angle, I was hitting the ball hard and flat up the middle and he struggled a little with that.

"I just tried to play tough points and make him have to play great tennis to win the tie-break.

"(Now) I need to up my game, get some good rest and hopefully I can get given an evening match because it's been seven days in a row I've played between 12 and three o'clock and it's been tough."

Murray, who successfully defended his title in Toronto last week, will face American wild card Mardy Fish in the quarter-finals, a player he has lost to twice this year.

"When I played against him this year I was really struggling confidence wise, I wasn't playing particularly well," Murray added on Sky Sports 4.

"Previously I played against him a few times and had good results against him, I quite enjoyed his game style. The last two have been tough but I feel like I'm playing way way better than I was a few months ago. If I play like I have been I have a chance of winning."