A couple odd losses and back issues later, Federer himself swapped the prototype for his trusted Pro Staff 90 during practice sessions in Cincinnati. He stated during interviews and press conferences (in four different languages) that he would put off racquet testing until the fall, after the US Open. The fall passed without the testing, and he continued to use the same racquet through the end of the season.
Now with more time again, the Swiss maestro is testing racquets. In keeping a very low profile other than a one week training session with Stefan Edberg, it is still unclear which racquet he will decide to play with in 2014.