Andy Murray will prioritise rest before beginning his preparations for his next tournament in Cincinnati in just over a week.
The three-time grand slam champion pulled out of the Citi Open ahead of his scheduled quarter-final clash with Australian Alex de Minaur in Washington on Friday night.
The former world No.1 cited exhaustion for his decision following a gruelling week that had seen him taken to three sets in all three of his matches and spend more than eight hours on court.
The 31-year-old, who only finished his third-round win against Marius Copil at 3am on Friday, said in a statement on the ATP website: "I won't be able to play my match tonight. I'm exhausted after playing so much over the past four days, having not competed on the hard courts for 18 months.
"I also need to be careful and to listen to my body as I come back from a long-term injury."
Tournament director Keely O'Brien had earlier caused controversy with comments to the Washington Post encouraging Murray to play.
O'Brien said: "I hope that Andy really takes into consideration this role in his sport and as a global role model to guys and girls on the tour and kids around the world that, when things are difficult and tough and the conditions aren't great, it's not OK to just give up."
O'Brien struck a different note in an official statement following Murray's withdrawal, saying: "I am so grateful that Andy, an incredible champion, came back to DC to begin what we all know will be a great comeback."