The midfielder revealed his ankle - injured when playing for Manchester City against Tottenham in early May - is fully recovered.
Barry is confident another week's training before the encounter in Cape Town will leave him 100% ready should he be required by Fabio Capello.
He told BBC Sport: "The ankle has been fine for 10 days. Another week's training in the lead-up to the Algeria game and I should be spot on.
"If the manager had asked me if I was ready to play against the United States at the weekend, I would have bitten his hand off to try and make the starting team.
"I was desperate for us to go two or three goals up and then he might have thrown me on!"