An emotional Andy Murray sobbed into his towel on the side of the court after a grueling victory over world No. 93 Marius Copil in Washington -- a game that finished at 3 a.m. local time.
Murray, who continues his return from hip surgery, overcame the Romanian 6-7 6-3 7-6 in his second three-set encounter in two days having previously defeated fellow Briton Kyle Edmund.
"Just the emotions coming at the end of an extremely long day and a long match," said the 31-year-old Murray, who sat crying into his towel for several minutes.
The former world No. 1 had to dig deep after conceding a 5-0 advantage in the first-set tie break to lose 7-5, but Murray twice broke Copil in the second set to force a decider.
The pair shared breaks in the third set, and as the clock ticked on later into the night, Murray eventually emerged victorious (7-4) in the final tie break -- at 3:01 a.m.
The three-time grand slam winner has slipped to world No. 832 during his injury rehab and is now chasing his first ATP title since March 2017.
He next faces Alex de Minaur in the quarterfinals in Washington. The Australian defeated South Korea's Hyeon Chung 6-2 4-6 6-2.