Barry is back training with the England World Cup squad in South Africa after suffering an ankle ligament injury towards the end of the domestic season.

It was a welcome boost for Capello on the day skipper Rio Ferdinand was ruled out of the tournament with a knee ligament setback.

Manchester City midfielder Barry did not participate in the training camp in Austria as he stayed to undergo rehabilitation work at his club.

He is improving day by day with the opening group game with the United States still eight days away.

But Capello is mindful that this is the "dangerous" period for Barry and is determined not to rush the comeback of the former Aston Villa player.

The Italian said: "About Barry, we are happy because he's improving every day and getting better and better with every moment.

"I spoke with him on Wednesday and he says he's really happy. There's no swelling and his confidence is rising. He is getting stronger.

"He will work harder every day and we will see what happens.

"But we will also go slowly. This is the worst period. If you go too fast, it's really dangerous.

"I'd prefer he didn't play against the USA and is fit for the other games. We have to be careful at every moment."

Barry is pivotal to England's chances of success in the tournament as the holding midfielder protecting the back four and allowing Frank Lampard and Steven Gerrard licence to go forward.

The fact Capello has allowed Barry so much leeway in giving him until the last possible moment to be part of his squad speaks volumes of what he thinks of the 29-year-old.

Barry is also desperate to participate in his first World Cup - a decade after first being picked by England.

He was overlooked by Sven-Goran Eriksson for the 2002 and 2006 finals in Japan and Germany respectively.