Barkley, 19, made his international debut as a substitute in England's 4-0 win over Moldova last week.
And Martinez said: "I am extremely excited about his future because I think he can reach unseen levels."
Barkley suffered a double leg break while on duty with England under-19s in October 2010 and his club manager claims that injury hell HELPED him.
"It's given him a unique maturity for such a young man," he said. "He's been through absolutely everything and that's made him who he is today."
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