Terry was sent for a scan on the knee injury he picked up in training on Wednesday this lunchtime but the problem area was so swollen, it was impossible to come up with a proper diagnosis.

Under the circumstances, and with the possibility of surgery suddenly being raised, coach Steve McClaren had little option other than to withdraw Terry from this weekend's Wembley encounter, which he might have missed anyway to save him from picking up a yellow card that would have seen him banned from next Wednesday's crucial trip to Russia.

However, given the time it has taken merely for the injury to ease, it seems highly unlikely Terry will make the journey to Moscow, leaving McClaren to trust Campbell's fitness, something he cannot be entirely content with.

After flagging up the possibility of restoring Campbell to England colours in the summer, a year after McClaren pitched him into the wilderness following the 2006 World Cup, the coach has seen the veteran defender pull out of his first two squads of the season with groin and hamstring problems respectively.

Campbell at least managed to join up this time around but subsequently missed training on Tuesday with an Achilles complaint.

Although the 33-year-old Portsmouth player now seems to have got over that problem, there must be some concern that by playing against Estonia, which he surely has to do in order to re-acclimatise himself with the international game, he will put his fitness at risk for the Russia encounter, when England need a draw to move to the brink of a place in next summer's finals.

With Jamie Carragher retired, Wes Brown back at Manchester United nursing a knee injury and Jonathan Woodgate so out of form at Middlesbrough he didn't even make the squad, McClaren's only other options are to introduce uncapped Everton defender Joleon Lescott or move Micah Richards, earmarked for the right-back slot, into a central position and bring in Phil Neville to fill the gap created by the switch.

It just emphasises how important Campbell is to England over the next few days, even if McClaren has not entirely given up hope of Terry making a rapid recovery.

"John Terry had a scan on his left knee today and will not be fit for Saturday's game against Estonia," confirmed McClaren.

"He will remain with the squad and his injury will be assessed on a daily basis with a view to Wednesday's match in Russia.

"During this time the England and Chelsea medical teams have been and will be in close communication."

With Terry out, Liverpool's Steven Gerrard will assume captaincy duties, with Michael Owen probably becoming his deputy.