McClaren facing loss of Terry for crunch qualifiers

Steve McClaren's England plans were thrown into doubt last night when it emerged that his captain John Terry will require a scan today on a knee injury that caused him to pull out of training. With Wes Brown already out and Sol Campbell struggling with an achilles problem, England are drastically short of replacements.

Terry is understood to be having the scan on his knee this morning at Chelsea's Cobham training ground where a decision will be made on whether he can play against Estonia at Wembley in the Euro 2008 qualifier on Saturday. It will be a major blow to McClaren, who was also counting on his captain for Wednesday's crucial game against Russia in Moscow.

The England captain was already wearing a mask to protect the depressed fracture of his cheekbone which he sustained in the Premier League game against Fulham. He only underwent surgery for that injury 13 days ago and has played with a broken toe since the start of the season – a problem which he treats with painkilling injections before most games.

Despite these two major injuries, Terry has continued to play on and McClaren will be hoping that the scan does not show any serious damage. However, the problem was bad enough yesterday that Terry limped out of training. The England players did a double session and the extent of the defender's injury was kept secret from even some Football Association officials.

Terry's potential absence is another reason for McClaren to rue Jamie Carragher's decision to retire from international football. He would be the ideal man to step into Terry's shoes but the Liverpool centre-half has resisted all attempts to persuade him to go back on the decision he made last summer. These are exceptional circumstances but Carragher is unlikely to change his mind.

The options for McClaren should Terry be ruled out look particularly bleak. In a position in which the England manager was once blessed with many internationals there are now few contenders. Sol Campbell would be an excellent option but he has not played for his country since coming on as a substitute against Sweden at last summer's World Cup finals. He is not yet fully fit. If he is not fully fit, McClaren has only Everton's Joleon Lescott as a specialist centre-half and he has never played for his country at a senior level.

To throw the 25-year-old into a Euro 2008 qualifier would be a major risk for the England manager. An alternative is to switch the 19-year-old Micah Richards from right-back to centre-back – where he plays for his club side Manchester City. The England manager could call upon Tottenham's Michael Dawson - not named in this squad - although presumably he feels that Lescott is a better bet.In terms of his midfield pairing, McClaren appears to be leaning towards picking Gareth Barry ahead of Frank Lampard.

Barry was impressive in the two previous Euro 2008 qualifiers and fulfils the function of a holding midfielder in Owen Hargreaves' absence. However, leaving a fit Lampard on the bench is a decision that McClaren has previously been unwilling to make. The Chelsea midfielder has played just one game since the end of August when he suffered a torn thigh muscle.

The England players have a day off today and will be told the team tomorrow after training at their Hertfordshire base. By then McClaren will know whether he has to go into two games that could define his career without his inspirational captain.