England manager Fabio Capello has refused to guarantee Jamie Carragher a place in his final 23-man World Cup squad despite the Liverpool defender showing his willingness to come out of international retirement by agreeing to be part of a 30-man provisional party.

Capello's quandries: the Engaland manager has left many unanswered questions with his initial squad

In all probability, having persuaded Carragher to make himself available, it is hard to see Capello not selecting the Liverpool veteran in his final squad when it is announced after the friendly with Japan in Graz on May 30.

However, he would not give Carragher any guarantees he would be on the plane to South Africa.

Capello said: "He is one of the 30 players. During the training camp I will evaluate the performance of each player, after that I will decide."

Detailing how Carragher's return to the international fold came about, Capello added: "We started two months ago, we spoke with him, [Capello's assistant] Franco Baldini met him two weeks ago and he was happy to stay with us and we decided to select him. I selected him because he is a really, really good player."

-- Read the provisional 30-man England squad for World Cup 2010

Another man to make it into the 30-man squad is Tottenham defender Ledley King. Capello called King into his squad for the double-header against Slovakia and Ukraine in April last year, but once it was discovered the Tottenham man's chronic knee condition prevented him from training he was quickly returned to his club.

However, with long-time squad men Wes Brown and Joleon Lescott ruled out by injury and doubts remaining over first-choice central defenders Rio Ferdinand and John Terry, Capello has decided it is worth checking out the experienced Carragher and King once more.

As for King's inclusion, Capello has no concerned about the defender's long-standing knee injuries.

"We were monitoring him for a long time," said the Italian. "He is one of the best defenders in England. In the last 15 days he has played four games, I spoke with him about the knee problems and he said this season the knee was really good.

"The reason I selected him is that he's good, a really good defender."

Capello revealed he had also asked Manchester United veteran Paul Scholes to consider a comeback but unlike Carragher, the midfielder turned down the request.

"Yes [I spoke to him] but it was up to him," Capello confirmed. "He said no, he preferred to stay with the family. But I tried, yes."

Capello has several possible injury headaches with question marks over the fitness of King, Gareth Barry and Wayne Rooney, while Owen Hargreaves missed out due to a long-term problem.

Asked about Barry, Capello said: "I decided this morning after meeting with Franco Baldini and the doctor. I decided to put him in the 30 because the next medical check will be May 24 and after this medical check we will decide what we can do.

"I hope after this he will be ready to start training. You have to wait."

He added: "I spoke to Owen twice in Manchester and he's not fit, not ready to play. He didn't play for 18 months and for that reason, I can't select him. He's a really important player when he is fit."

Capello insists there are no injury doubts surrounding captain Rio Ferdinand and confirmed Barry is the only current doubt.

"I am not concerned about these players," he said. "Yesterday I spoke for a long time to Sir Alex Ferguson and he told me Rio is fit, he can play, no problems.

The Italian coach revealed Bobby Zamora was unlucky to miss out.

"It was one of the last decisions that I took," he revealed. "I spoke to him and it was up to him because he can't train every day, he plays always with injections and probably he needs an operation (on his Achilles)."

One of Capello's 'wild cards' will be Manchester City winger Adam Johnson. "He is a really interesting player," said the England manager. "He played very well in the second part of the season with Manchester City. He's one of the younger players most interesting in the Premier League and I want to check him out during the training camp."