Bothered by back, Roger Federer loses US Open quarterfinals to Grigor Dimitrov

Grigor Dimitrov, of Bulgaria, watches a return to Roger Federer, of Switzerland, during the quarterfinals of the U.S. Open tennis tournament Tuesday, Sept. 3, 2019, in New York. (AP Photo/Seth Wenig)
Roger Federer, of Switzerland, thanks the crowd after a loss to Grigor Dimitrov, of Bulgaria, during the quarterfinals of the U.S. Open tennis championships Tuesday, Sept. 3, 2019, in New York. Dimitrov won 3-6, 6-4, 6-3, 6-4, 6-2. (AP Photo/Charles Krupa)SoundThe gallery will resume insecondsShow C