Sir Andy Murray converted on his seventh match point to beat Mackenzie McDonald in three sets and set up a tie against fellow Brit Kyle Edmund at the Citi Open.
The two-time Wimbledon champion toiled for more than two-and-a-half hours against world number 80 McDonald, eventually taking the match 3-6 6-4 7-5.
McDonald, 23, broke two of Murray's opening three service games and wrapped up the first set 6-3 inside 40 minutes.
But Murray drew things level, taking a crucial game nine in the second for a 5-4 lead and serving out the set.
A 73-minute deciding set followed, in which Murray took an early break and found himself 5-4 up and serving for the match.
But McDonald saved five match points and converted his second break point to draw things level at 5-5.
Murray broke back immediately for a 6-5 lead following a controversial call when McDonald's racket was adjudged to have crossed the plane of the net at 30-30. The former British number one then made no mistake in serving out the match.
The 31-year-old skipped Wimbledon earlier this year and is playing in Washington as he continues his protracted recovery from long-term hip trouble.
Murray had surgery on his right hip in January, only returning to action on June 18, facing Nick Kyrgios at Queen's.
"It was a tough, tough match," Murray said on the ATP website.
"It could have gone either way. Obviously, if you lose a match like that, it's a tough one. When I lost to (Teymuraz) Gabashvili here (three years ago), I lost serving for the match, so I was thinking about that a little bit, too. It is just nice to get through."
He added: "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.
"Made a few little adjustments here and there. But mentally, it was a big one to get through."
He later overcame Stan Wawrinka at Eastbourne, only to lose in straight sets to Edmund two days later.
PA
