The sting of loss rarely cuts deeper than this. When Javokhir Sindarov — the 19-year-old Uzbek prodigy who replaced Viswanathan Anand as a late entrant — drew Hikaru Nakamura as his quarter-final opponent at the Weissenhaus Freestyle Grand Slam, few anticipated the humiliation that would follow for the veteran American. Nakamura suffered one of the worst losses of his career, and as the tour moved from Germany to Paris for the second leg, he was feeling the weight of creeping self-doubt. The manner of his collapse against Sindarov, squandering winning positions through uncharacteristic mental lapses, left the five-time US champion contemplating retirement. “Sometimes, things happen for a reason and if I’m going to start losing games where I get into great positions but my brain stops working, it starts to lead to certain thoughts creeping into my mind about the future,” said Nakamura, referring to his potential retirement. “If I get into similar situations where I start messing up games like I messed up a couple of games in this freestyle event against Sindarov and …