Andy Murray set up a meeting with fellow Briton Kyle Edmund by beating Mackenzie McDonald on his return to action in Washington.
The former world number one skipped Wimbledon saying he was not ready to play five-set tennis following hip surgery earlier this year.
Instead he focused on practising on the hardcourts to prepare for the forthcoming US Open and Monday’s clash was his first step on that road in terms of matches.
The Scot, playing just his fourth match in a year and his first on a hard court since March 2017, dropped the first set but fought back to post a hard-fought 3-6 6-4 7-5 victory in two hours and 37 minutes.
He squandered five match points when serving for the match at 5-4 in the deciding set but, having had his serve broken, he hit back straight away after his American foe was penalised for hitting the ball on the wrong side of the net.
Murray made no mistake in serving out second time round and afterwards said: “It was a tough, tough match. It could have gone either way.”
He admitted his 2015 first-round defeat at the same Citi Open tournament had preyed on his mind at times.
“When I lost to (Teymuraz) Gabashvili here, I lost serving for the match, so I was thinking about that a little bit. It is just nice to get through. I wasn’t dictating many of the points. I wasn’t hitting the ball that cleanly. I just fought and tried to make it tough for him.”
“Mentally, it was a big one to get through.”
Murray will face Edmund in round two with the current British number one having beaten him last month on the grass of Eastbourne.
The 31-year-old is also due to play in Toronto next week and then Cincinnati prior to the US Open which starts on August 27. It has also been announced that Murray has signed up to play in October’s China Open where world number one Rafael Nadal is among the entries.