He has also withdrawn from next week's Rogers Cup in order to recover, Xinhua news agency reported.
He was to have met Australian Alex de Minaur in the Washington quarter-finals on Friday. "I don't know how players are expected to recover from that", Murray said after the Copil win.
Norrie won almost three-quarters of his first serve points as he dismissed the fourth seed and world number 25 to reach his second successive ATP Tour semi-final. Zverev joked after advancing, "I think I'm the only one that's allowed to buy a drink in the US, right?"
"Finishing matches at 3 in the morning is not good", he said, per The Post.
The 19-year-old Tsitsipas is coming off his first run to the fourth round at a Grand Slam tournament, last month at Wimbledon. "I don't think it's reasonable", Murray said.
Georgia Hall wins Women's British Open for first career major title
Hall was always chasing, but was given hope when Pornanong bogeyed No. 8 to reduce her lead to one shot. She birdied three of the last four holes to join Pornanong in the final group on Sunday.
The former British world No 1 has played just three tournaments since returning from hip surgery in January - losing to Nick Kyrgios at Queen's and seeing off Stan Wawrinka before falling to Kyle Edmund at Eastbourne.
"I'm giving my view right now as someone who's just come back from a very, very long injury layoff", he said.
He also told reporters that he could "potentially" withdraw from the tournament rather than take on De Minaur.
Asked after beating Copil how his body is holding up, Murray replied: "It doesn't feel great, just now".
"I've played quite a few matches this week in Washington and I need to be smart with my rest and recovery as I come back from injury".
"Not a whole lot, really, the emotions coming out at the end of an extremely long day and a long match", Murray said of what made him so emotional. "By the time you finish doing recovery and everything it's 5.30 or 6 o'clock in the morning".
Murray looked set to win the opening set against Copil, ranked 93, after moving 5-0 ahead in the tie-break only for the Romanian to reel off seven points in a row.