Manchester City midfielder Gareth Barry has been given another week to prove his fitness ahead of the World Cup which starts in 16 days' time.
The 29-year-old former Aston Villa stalwart is struggling with the ankle ligament injury he picked up earlier this month in the crucial 1-0 home defeat to Tottenham Hotspur.
Barry is continuing to undergo tests on the injury but as yet it is uncertain whether he will be fit enough to face the USA on June 12.
Capello has to name his 23-man squad on June 1 but will give Barry every opportunity to prove his fitness.
The 63-year-old Italian said:"Barry always played with me. After Owen Hargreaves it was Gareth Barry. He is one of the important players, really important.
"If Barry is fit, he will come with us. If not, he will stay at home. He is one of the players we want to be fit."
FIFA rules allow managers to replace any player ruled out through injury after the final squads are confirmed up to 24 hours before the first game so Capello could include Barry in his squad next Tuesday and then replace the midfielder if he fails to shake off the problem.
Capello has included Barry in his starting eleven in 19 of the 22 England matches the former Real Madrid and AC Milan coach has overseen.