Both defenders picked up problems in the 1-0 friendly win over Belgium, Cahill injuring his jaw and Terry his hamstring.
However, Sir Trevor Brooking, the FA’s director of football, expects the pair to overcome their injuries.
"Gary was certainly our initial main concern last night," Brooking told the BBC's 'Sportsweek' programme. "He had a scan last night. At the moment the feedback is that we are hoping it is not cracked.
"It was his jaw following the collision and they were concerned that it was cracked and it might have put him out of it [Euro 2012]. At the moment we're hoping it's not. I'm sure they'll have a second look but at present we're hoping that's okay.
"John Terry had a hamstring issue that will be scanned this morning. The medical staff are hopeful that it is not bad enough for him not to be able to stay in the squad."
Captain Steven Gerrard admitted that losing Cahill would be a serious set-back for the squad.
"It will be a huge blow if Gary is ruled out," Gerrard told Sky Sports News. "He's had a fantastic six months since he's gone to Chelsea and we need him out there. It will be a huge blow if he is out."