 Towards the middle of July , Federer hired Pete Sampras ' old coach Paul <unk> on a trial basis to put his tennis game and career back on the right path . At the 2010 US Open , Federer reached the semifinals , where he lost a heart @-@ breaking five @-@ set match to Novak Djokovic after holding two match points . Federer made it to four Masters 1000 finals , prevailing at the Cincinnati Masters against <unk> Fish . 
