The chief executive of US sportswear group Nike has resigned following "differences" with the firm's founder.
Nike is the world's largest athletic shoe maker
William Perez leaves 13 months after joining the firm and has been replaced by a Nike veteran, Mark Parker.
Although profits rose after the arrival of Mr Perez, Nike has faced increasing competition in Europe and Japan.
Mr Perez joined from household products maker SC Johnson and was the first person other than founder Philip Knight to hold the top position at Nike.
"Succession in any company is challenging, and unfortunately the expectations that Bill and I and others had when he joined the company a year ago didn't play out as we had hoped," Mr Knight said in a company statement.
Mr Perez said that he and Mr Knight "weren't entirely aligned on some aspects of how to best lead the company's long-term growth".
Although Nike's most recent results saw a 15% rise in second quarter profits, there were fears that sales growth was slowing because of lower demand from Western Europe and Japan.
Nike shares have fallen 3% in the last 12 months on investor concerns that it is facing more competition from German rival Adidas-Salomon, which is in the process of buying US sportswear firm Reebok.
New boss Mark Parker joined Nike in 1979 and took main responsibility for the development of the Nike Air brand.