The Wimbledon "L" clearly ain't affecting Serena Williams ... the tennis legend was out partying in Hollywood on Thursday -- and she looked GREAT!!!!
The 37-year-old superstar hit up Sunset Room for the Sports Illustrated "Fashionable 50" party -- you know, the one where they honor the 50 hottest athletes in the world -- and Serena killed it.
Obviously, some thought a rough loss to Simona Halep on Saturday might hamper her style ... but, clearly, there ain't no hangover here!!
Other celebs crushed it too ... Michelle Wie, Errol Spence Jr.