England striker Darren Bent is a major doubt for Friday's Euro 2012 qualifier in Bulgaria after he once again missed training.
Bent, who already had missed the previous two days' sessions with a groin problem, failed to participate in the final session on Thursday afternoon.
The Aston Villa player also missed last month's friendly international against Holland - subsequently postponed because of the London riots - with a shoulder setback.
The former Sunderland player had looked to be establishing himself as a regular member of Fabio Capello's attack after a spell of three goals in three matches. But his possible absence for the trip to Sofia could open the door for Jermain Defoe, who scored a hat-trick against Bulgaria at Wembley a year ago.
Bent was the only absentee from training as England finalised their preparations for two games in four days, which will go a long way to determining whether they gain automatic qualification to next summer's finals.
However, England boss Capello is happy with his fire power ahead of the double-header and is convinced Wayne Rooney's hat-trick against Arsenal last week can provide the perfect medicine for an end to his international goal drought.
Rooney has scored just one goal for England in two years, but Capello feels the injection of confidence the 25-year-old gained against the Gunners, in addition to the boost provided by United's dazzling array of younger players, leaves him on the verge of making a big impact for the Three Lions.
"Goals are a fantastic medicine for a forward,'' said Capello. "Now is a good moment for him. The spirit of Manchester United is different. Those young players have put something different on the pitch.''
There is also a growing feeling that Phil Jones may be handed his first cap too given the excellence of his performances during United's opening three Premier League games. It means the player most likely to miss out is Tom Cleverley.
Capello was giving little away, though. "I will decide tomorrow,'' he said. "It is interesting for me because I can select young players when they play in the Premier League. They have found such confidence. I have some ideas, but I also have to be careful.''
England will follow up the trip to Bulgaria with a home encounter against Wales at Wembley on Tuesday.