The USA youngster is set to spend his season on loan with Hamburg rather than fighting for minutes with Bayern Munich.
The move was first reported by Sky Sports, with ESPN FC confirming the deal through Green's American father.
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Green, who scored for the USA in the World Cup this summer, was not likely to see an abundance of playing time with Bayern's first unit despite the club being involved in the Champions League. The move to Hamburg should at least offer the youngster a chance to compete for regular playing time.
As part of the ESPN FC report, Green's father made it clear that the move would be for just one year before a return to Bayern.