Bath's Olly Barkley could miss England's crucial RBS 6 Nations showdown at Lansdowne Road next Sunday after the player sustained a calf injury on Thursday, while prop Phil Vickery is out for the rest of the series after breaking his arm playing for Gloucester in their 17-16 win over Bath in the Premiership on Saturday.
Barkley, who played in the centre during England's 18-17 defeat to France at Twickenham last week, was due to start Bath's West Country clash against Gloucester today.
But the 23-year-old failed to complete a club training session yesterday morning.
Bath head coach John Connolly had also hoped Barkley would pass a late fitness test ahead of the Zurich Premiership clash - but the player was not given the all-clear.
A Bath spokesperson said: "At the moment we believe Olly has tweaked his calf muscle but he will be going for scans at a hospital in Bath tomorrow which will give us a clearer picture."
Vickery returned to international action only this month after having neck surgery and losing his place to Julian White, who is also ruled out of the Irish match through injury.
The absence of the two experienced front rowers leaves England without a recognised tighthead in their 30-man training squad and could lead to a call up for Bath's Duncan Bell or Northampton's Robbie Morris.
With two defeats out of two for reigning world champions England in this season's Six Nations the injury news will come as a massive blow for head coach Andy Robinson.
Robinson already has a side awash with injured players, including Mike Tindall, Jonny Wilkinson Julian White and Richard Hill.