Brazil's Gustavo Kuerten will be out of action for up to six months after more surgery on his recurring hip problem.
Kuerten has been dogged by hip problems
The 28-year-old had an operation in Pittsburgh to remove cartilage. He had surgery on the same hip in 2002.
Since then he has struggled to regain the form which took him to the world number one spot as well as his three Roland Garros titles.
Kuerten told the O Estado de Sao Paulo newspaper he wanted "to be able to return to play without pain".
He will remain in America for three weeks before returning to Brazil, and he will be able to begin light exercises to strengthen his muscles after a month.
Kuerten is currently ranked 27th in the world.
Earlier this year, he pulled out of Wimbledon as his hip continued to cause him problems.