Two months after muttering an anti-gay slur on the golf course ... Justin Thomas was back holding up a trophy -- winning the Players Championship on Sunday at TPC Sawgrass.
The 27-year-old lost several major sponsors -- including Ralph Lauren -- back in January after television mics caught him using the F-word during a round at the Sentry Tournament of Champions in Hawaii.
Thomas had missed a 5-foot putt ... and, as he kicked the ensuing shot into the hole, he said "f*****" under his breath.
Thomas later called the incident "inexcusable" and apologized .