Britain's Andy Murray beat Mackenzie McDonald 3-6 6-4 7-5 in the Washington Open's first round in his fourth match following hip surgery in January.
Murray, 31, converted his seventh match point after more than two-and-a-half hours on court against the American.
"Mentally, it was a big one to get through," said former world number one Murray. "I fought hard and I had to. The movements and stuff were fine."
He will now play fellow Briton Kyle Edmund, 23, in the second round, reports BBC.
Edmund beat Murray at Eastbourne in the third match of his return during the grass-court season before the Scotsman pulled out of Wimbledon as he felt it was "too soon" to play five-set matches following his rehabilitation.
"I'll have to play much better if I want to win that match, more aggressively," Murray said. "It will help having one more match under my belt."
Murray had been out of action since Wimbledon 2017 before having his operation at the start of this year.
After the Citi Open in Washington he also hopes to play Masters-level events in Toronto and Cincinnati in preparation for the US Open.