England flanker Tom Wood has emerged as a doubt for Saturday's Six Nations clash with Wales at the Principality Stadium due to a shoulder injury.
Wood picked up the problem during his side's narrow 19-16 victory over France at Twickenham last weekend and has been unable to train with his teammates so far this week.
The Northampton Saints flanker is now in a race against time to be fit for the trip to Cardiff as Eddie Jones's side look to extend their record winning streak.
Should Wood fail to recover in time then Jack Clifford is the most likely replacement, which would leave England with an inexperienced back-row for the second match of their title defence.
Clifford, Maro Itoje and Nathan Hughes have just four international back-row starts between them, compared to 147 for Wales trio Sam Warburton, Justin Tipuric and Toby Faletau.
Chris Robshaw and Billy Vunipola are expected to miss the entire tournament for England, while James Haskell is still not fit enough to start having only recently returned from a seven-month injury layoff.