Cracks appearing in England's Terry-Ferdinand defensive rock

John Terry and Rio Ferdinand may have developed a solid England partnership in recent years, but doubts are starting to be raised about the two central defenders ahead of the football World Cup.

With more 130 caps and a wealth of tournament experience between them, England's previous and current captains should be certain starters for the finals in South Africa in June.

But if coach Fabio Capello were looking at this season's domestic form alone, both would struggle to make the team.

Terry's form has dipped since newspaper revelations in January that he had an extramarital affair with the former partner of England team mate Wayne Bridge.

Stripped of the England captaincy as a result, Terry continued as Chelsea skipper but even fans of the Stamford Bridge club would acknowledge that ''JT'' has been badly off the pace at times in recent weeks.

On Saturday, he gave an error-strewn display and was sent off in the second half after two clumsy challenges as the Premier League leaders lost 2-1 at Tottenham Hotspur.

Terry suffered in comparison with Tottenham's improving centre back Michael Dawson, who could yet make a late dash into the World Cup squad, and Carlo Ancelotti's words of support after the game had a hollow ring.

"People are looking too much at John Terry's performances," said the Chelsea coach. "He is doing very well.

"He did a fantastic season," added the Italian. "Maybe sometimes he had some problems and didn't play so well, maybe against Tottenham he didn't play too well, but he has been absolutely fantastic."

If "absolutely fantastic" means misjudging simple long balls, cumbersome turns, ill-advised handballs, and mediocre defending, then Ancelotti is spot on in his analysis.

Terry was embarrassed by Everton's Louis Saha in Chelsea's 2-1 defeat at Goodison Park in February and the England centre half said he was disappointed with his display.

Last month, though, he declared himself generally pleased with his form through the season.

Terry delivered his usual heart-on-the-sleeve show for England in a friendly against Egypt, showing strong character to come through so soon after losing the captaincy, but it will need more than bravery in the tackle and clenched-fist exhortations to keep the world's leading attackers at bay.

Ferdinand has also had his troubles this season. A succession of injuries, including a long-running back problem, have limited him to short bursts of action for Manchester United followed by spells in the treatment room.

Long odds would be available on the 31-year-old getting through seven games in a month should England go all the way to the final in his fourth World Cup.

Ferdinand is never short of confidence, but for it to be justified he needs to be playing regularly, to ensure his timing, positioning, and anticipation are cent per cent.

Capello's back-ups — Matthew Upson of West Ham United, Manchester City's Joleon Lescott, and Wes Brown of Manchester United — are steady league performers without carrying the aura of potential World Cup winners.

England hopefuls Dawson, Ryan Shawcross of Stoke City, and Everton's Phil Jagielka probably offer more pace, mobility, and just as much aggression.

The situation must be a concern for Capello, especially as the full back and goalkeeping positions also appear fluid.

That will probably work in favour of the Terry-Ferdinand axis as the coach will want stability of selection somewhere, but that backdrop is hardly the foundation stone he would have been hoping for.