Wales and Newport centre Andy Marinos has revealed he is suffering from deep vein thrombosis (DVT) but stressed it is not serious.
Marinos, 30, who has already ruled himself out of this year's RBS Six Nations, developed the blood clot in his lower leg while recovering from damaged ligaments in his foot.
"I'm in a race against time at the moment," Marinos told BBC Wales Sport. "I had anticipated being back in the middle of March, but the DVT has obviously set me back a couple of weeks.
"I'm hoping to be playing at least the month and a half of the season and try to stake a claim to get into the World Cup squad."
DVT, that occurs when clots form in deep blood vessels, is often associated with long-distance air travel and is potentially fatal.