Chelsea and England centre-half John Terry is undergoing a "precautionary scan" on his right foot after picking up a knock in training today.

The news comes as a blow for Chelsea's preparations as they attempt to win the double when they face Portsmouth in Saturday's FA Cup final and if it proves to be a more serious problem, his participation in the FIFA World Cup™ could be in doubt.

A statement from the club said: "John Terry has today taken a knock in training and has gone to hospital for a precautionary scan on his right foot. He left Cobham walking freely in a protective boot, and we await the results which are expected on Thursday."

It also gives England coach Fabio Capello a headache as he prepares for the FIFA World Cup in South Africa and the Italian will undoubtedly be monitoring the situation carefully. Terry, stripped of the England captaincy following allegations about his private life this season, was yesterday named in Capello's provisional 30-man FIFA World Cup squad alongside fellow centre-halves Rio Ferdinand, Jamie Carragher, Michael Dawson, Ledley King and Matthew Upson.

Should the injury rule Terry out of Saturday's Wembley showpiece it would represent the latest in a line of pre-tournament injury scares for England. Manchester United striker Wayne Rooney limped out of Sunday's match against Stoke but, like Red Devils colleague Rio Ferdinand, has received a positive diagnosis from his club. Midfielder Gareth Barry is Capello's biggest ongoing injury concern while David Beckham was ruled out of the tournament earlier this season.