Jack Draper, once the leading British player, has pulled out of a tournament just before it starts because of continued discomfort from a long-term arm injury.

The 24-year-old left-hander has withdrawn from the ATP Tour stop in Washington, which would have marked his return after opting out of Wimbledon last month.

Draper has dealt with bone bruising in his serving arm for over a year, though he mentioned at the weekend that he was feeling physically strong ahead of the Mubadala DC Open.

He appeared fit during practice with his new coach Andy Murray, yet he exited the ATP 500 event on Monday after noticing increased soreness in the affected arm.

This marks another setback for Draper, echoing the situation at the All England Club where he expressed optimism about his condition before withdrawing a day prior to his opening match.

"These last months have felt like nothing but adversity and setbacks," Draper posted on Instagram following the announcement of his withdrawal.

"Most days I have faced doubt, while remaining hopeful that I can continue making positive progress and finding ways to move ahead.

"Staying patient with the process has been my greatest test, but I know I am getting nearer to my goals."

Draper still hopes to compete in Montreal and Cincinnati before the US Open begins on 30 August, where he reached the semi-finals last year.

Even so, this development raises concerns and highlights a troubling pattern with an injury he calls complicated.

The former world number four has contested only 14 matches in the past year, mainly due to the bruised humerus that he has managed through extended rest periods.

"It is difficult to know when to push forward and when to hold back," Draper noted at Wimbledon.

"Ultimately I play an aggressive sport where pushing through discomfort is sometimes necessary. At times it proves too much, while other times it does not.

"I would not enter any event if there was a real risk of making things significantly worse."

Draper's early season return was interrupted by knee tendinitis, and the three-time ATP winner had been sidelined for more than two months before competing at Eastbourne in June.

His semi-final run there came at a cost, as the arm injury resurfaced at Wimbledon and left him devastated to miss his home Grand Slam.

Now ranked 147th, Draper has not appeared in a major since the US Open last August.

Should he recover in time for Flushing Meadows this year, he would need to navigate qualifying or receive a wildcard for the main draw.

In Washington, lucky loser Mackenzie McDonald will take Draper's place in the draw.