Chelsea boss Claudio Ranieri has reassured Sven-Goran Eriksson that he can rely on John Terry to underpin England's injury-hit defence at this summer's Euro 2004 finals.

Eriksson is facing a considerable headache over his central defenders ahead of the tournament, with Rio Ferdinand already ruled out due to suspension.

Jonathan Woodgate is expected to be out for another five weeks with a torn thigh muscle, while Gareth Southgate is also facing a race against time to recover from a knee injury that has curtailed his Premiership season.

Ledley King is, meanwhile, suffering from a hip condition, while Eriksson has revealed his belief that Wes Brown is ''still not what he was before injury'' despite his recent improved form.

No wonder, therefore, that Eriksson's assistant, Tord Grip, was due to watch Matthew Upson in action for Birmingham City against Arsenal this weekend even though the defender has not been included in the past two England squads.

Sol Campbell, who has been protecting a groin problem for the past three months, is also expected to feature at Highbury, while vowing not to rest before the end of the Premiership season despite Arsenal's early title success.

''I've got to look after myself. I need to stretch my leg and groin, and give it rest and massage, as well as having treatment now and again. I have to be sensible,'' said Campbell.

''But I don't think I'll be resting now. You want to keep playing to stay sharp. We've got the European Championships at the end of the season and I don't want to be missing a few games and then try to start playing again. I want to keep going.''

While Anthony Gardner and Zat Knight are on the fringes of Eriksson's thoughts, and Jamie Carragher and Danny Mills could fill in, the Swede now has just one first-choice, fully-fit centre-back at his disposal - Terry.

The 23-year-old Chelsea vice-captain did not make his senior England debut until last summer's friendly against Serbia and Montenegro, but he has started six of seven internationals this season.

And while Campbell remains Eriksson's defensive cornerstone, Terry's potential importance to his country this summer is growing with every negative injury update on one of his rivals.

Ranieri nevertheless insisted: ''John Terry is one of the best centre-backs in not only England but in Europe. He commands the whole defensive line and is a good example and a good leader. He's young but he has a very long future.

''Sol Campbell is also a good player, as is Woodgate. I think there are a lot of very good centre-backs in England. Eriksson can therefore be calm without Rio Ferdinand.''

l Tottenham striker Jermain Defoe is on standby for a possible call-up to the Euro 2004 squad if Darius Vassell fails to recover from injury in time for the tournament.

Vassell has effectively been ruled out of the rest of Aston Villa's Premiership campaign with a hamstring problem sustained last weekend at Middlesbrough.

The striker is still hopeful of making the final 23-man squad, with Eriksson placing great faith in players who have produced consistent performances at international level.

Vassell's four goals in 16 caps, allied to his experience of having played at the 2002 World Cup, could give him added time beyond the announcement of the provisional squad on May 17 to convince Eriksson to include him.

However, the England coach can only take so many risks on players' fitness and, if the likes of Woodgate and Kieron Dyer are still doubtful, he could be more conservative in other areas of the squad.

Defoe, 21, and Alan Smith would therefore be the leading contenders to be chosen as the fourth frontline striker if the need arises.

While Smith has greater international experience, Defoe was impressive on his England debut last month when he replaced Vassell due to an early injury in Sweden.

Tord Grip, Eriksson's right-hand man, revealed: ''We have watched Jermain Defoe for his club and he has been impressive.

''Sven will pick a squad of 23 in mid-May but we have about 30 in total who are being considered. I would say that Jermain Defoe is certainly one of those players.''