Chicago Bulls star Luol Deng has suffered a fresh setback in his battle against a stress fracture, putting his availability for Great Britain this summer in further doubt.

Deng has missed 18 straight games for the Bulls with a stress fracture in his right shin, and admitted he felt sharp pain after trying to step up his rehabilitation program this week.

"I increased the workout a little bit and had a great deal of pain," Deng said in comments reported on the website of the Chicago Sun-Times.

"So I'm just going to try and be off of everything for a little bit again."

Deng has been trying to avoid surgery so as to be available should the Bulls make the play-offs, as well as for his country this summer with EuroBasket looming in September.

With five games left in the NBA regular-season, Deng seems certain to miss the rest of the campaign, but is not yet giving up hope of playing again soon with the Bulls well-positioned for a play-off berth.

Asked if his season was over, Deng said: "I don't want to get to that point. Even if I'm capable of being back for five or 10 minutes, whatever, so guys can sit down a little bit because guys are playing a lot of minutes I can help out.

"Now I can't even scrimmage for five minutes let a lone go and play. I'm hoping next week to try and increase it again and see how it goes."

Deng has expressed his determination to play for Great Britain in Poland in September, having played the lead role in their unlikely rise from Division B to qualify.

However, he also admitted last month that his Chicago paymasters will have a big say in the final decision, and the injury's failure to respond to rest so far will have GB coach Chris Finch increasingly worried about his star player's availability.