Jordan Henderson has been put on standby notice after Frank Lampard pulled up in training on Wednesday with a thigh problem.
The England squad had been stepping up their preparations for Saturday's friendly against Belgium when Lampard picked up the injury.
The extent of the damage is not yet clear but Lampard will be assessed by the medical team and sent for a scan on Thursday.
It will be a major blow if the midfielder is ruled out of Euro 2012 as he has 90 international caps and finished the season in fine form to help Chelsea win the UEFA Champions League.
While Lampard continues to be monitored, the Football Association has confirmed that Henderson has been put on alert.
The Liverpool youngster was named as one of Roy Hodgson's back-up options for the tournament in Poland and Ukraine despite a difficult first season at Anfield.
Lack of experience
If the 21-year-old is called up in place of Lampard it would leave the Three Lions with a lack of experienced alternatives in central midfield after Gareth Barry's earlier withdrawal from the squad.
Barry was replaced in the final 23-man squad by defender Phil Jagielka as Hodgson decided to 'reconfigure'.
Scott Parker has given assurances over his fitness after a recent Achilles problem, and looks set to start alongside captain Steven Gerrard in Poland and Ukraine.
The versatility of James Milner, Phil Jones and Alex Oxlade-Chamberlain may also come in handy for Hodgson.