Disgraced sprinter Dwain Chambers' debut season in the NFL Europe is over after he suffered a fatigue fracture to his right foot.
Chambers served a two-year ban for taking steroid THG
Chambers was looking to make a career playing American football for the Hamburg Sea Devils after serving a two-year athletics ban for using drugs.
The 29-year-old back-up wide receiver will not need surgery on the fracture but cannot risk further injury.
"I've no idea how this happened but I've never felt so much pain," he said.
The news comes just days after the NFL Europe said it would subject the former European 100m champion to extra drug testing "because of his background."
Earlier this week, Chambers courted controversy when he told the BBC drug taking was still rife in top-class sport and that drug cheats would always remain one step ahead of the authorities.
"It's simple, science always moves faster than the testers," he said.
"Some people take chances, some don't, and I was willing to take that chance.
"I was under the assumption that I wouldn't get caught."