Britain's Andy Murray saved a match point as he came back from the brink to beat Grigor Dimitrov and reach the last eight at the Cincinnati Masters.
Second seed Murray trailed 5-2 in the final set but recovered to win 4-6 7-6 (7-3) 7-5 after almost three hours.
"There were many, many important points in that match," he said. "I'm not quite sure how I managed to get through it."
Novak Djokovic and Roger Federer also progressed, but Rafael Nadal lost 5-7 6-4 7-6 (7-3) to Feliciano Lopez.
Murray will face Frenchman Richard Gasquet next, after the 12th seed defeated US Open champion Marin Cilic 7-5 6-3.