Holger Rune, the sixth seed could see his chances in doubt for Wimbledon before the tournament has even began.
Rune interrupted his practice on Saturday after thirty minutes due to an upper back injury. He has since received treatment and seemed fine.
"It happens. I'm not worried because I know that when it's muscular it's not serious. I need massage and treatment," he told DR Sporten.
"I've trained well all week. Have developed the things I want so I don't need to be on the pitch much now."
But there was some concern with his mother saying briefly to TV2. "I still don't know anything at the moment but they tell me that he is undergoing physical treatments."
In the run-up to Wimbledon, he played at the Queen's Club Championships and showed no sign of any issues in losing to Alex de Minaur.
But ahead of facing George Loffhagen, it could see the Brit who will likely give the tie a more centre court billing hoisted as an outside bet for many due to potential concerns surrounding the Dane.