Liverpool are waiting on the results of a scan that threatens to rule Steven Gerrard out of action for three to four weeks.
The midfielder hobbled out of England's 2-1 defeat by France at Wembley on Wednesday after Fabio Capello reneged on an agreement not to play Gerrard for more than an hour.
The Italian justified the decision, saying he needed the vice-captain to stay on because slight injuries had forced Rio Ferdinandand Gareth Barry to come off at half-time.
That is of little comfort to Liverpool, who could now be without their inspirational captain for six games - including difficult trips to Tottenham and Newcastle in the Barclays Premier League - because of a 'significant' hamstring injury.
The club's top medic Peter Brukner said: 'He's been in for an early assessment here and it certainly looks like a significant hamstring injury.
He's just heading off for a scan and we should have the results of that tonight. He's going to be out for a little while, I'm afraid. I'd imagine it could be three to four weeks.'
Gerrard limped away from Wembley Stadium last night and said: 'It's not good.'
It sparked an instant angry response from Roy Hodgson's coaching department. On his Twitter page, Liverpool'shead of fitness and conditioning, Darren Burgess, wrote: 'Unbelievable from all associated with England and English FA with regards to SG's injury.
'Completely ignored agreement and past history. Completely amateurish and now we pay for their incompetence. Absolutely disgraceful.'
Despair: England captain Steven Gerrard cannot hide his feeling as he limps off the Wembley pitch
But Capello explained: 'Wespoke with Steve and said he would play one hour but, after Barry's injury we had problems.
'That was the reason he stayed onthe pitch. If it's possible, the players will play the time we agreed with the club. But Barry was injured so we needed someone senior on the pitch.
'We are upset about what happened to Steve, of course. He has a problem and we will have to wait for the scan.
'They asked that he play one hour ifit's possible but they can't decide how long a player plays with thenational team. If it's possible, he would have played an hour. Iunderstand why they're upset, and I'm also upset.'
By midnight, Burgess had deleted his tweets, although it was unclear if that was done after an edict from Liverpool.
Brukner today tried to play down the spat, saying: 'If you put your hand up to play for your country, you've got to accept how long they want you to play for.
Concern: Newcastle feared Andy Carroll (No 9) wasn't fit to make his England debut
Under fire: Manager Capello
'Therewere obviously circumstances last night which came together to result in Steven playing for a bit longer than we'd hoped, which is disappointing but there's nothing we can do about that now.
'We'll move on and work as hard as we can to get him back playing for Liverpool as soon as possible.'
Earlier Capello's assistant Franco Baldini had felt obliged to phone Newcastle manager Chris Hughton and explain why Andy Carroll was starting against the wishes of his club, who were worried he might aggravate a groin injury.
Stokeboss Tony Pulis has weighed into the controversy by saying that national associations should pay players' salaries and medical bills if they call them up for international friendlies.
'Forfull-blooded international games, proper games when they are qualifyingfor a major tournament, then there is no problem with sending the players away,' he said.
'Thereis nothing better than playing for your country but that is in proper games not friendly matches and I think it has shown again last night with the team Capello played.
'He has played a lot of young players and given people a chance but they are like pre-season games.
'Ifthey want to do friendly matches then they should pay the wages and if they come back injured they should look after all of that. I think that would see friendly games dramatically subside.
'Whatdid they get at Wembley last night, 85,000? That is helping to pay for the stadium as much as anything else in my opinion.'
You disgrace! Liverpool attack Capello after Gerrard injured in England flopEngland 1 France 2: Capello's youngsters fail French test as kids are outclassedMartin Samuel: France turn on the style while Fabio turns back the clockTime for the FA to pay! Pulis leads call for compensation after Gerrard blowRoy to pick up an Oscar as Liverpool told to follow up interest in KranjcarLIVERPOOL FC