Robert Griffin III -- #IBelieve In Women's Team ... We're Good Friends Now

A super embarrassing moment on social media paid dividends for Robert Griffin III -- 'cause the NFL star says he's "good friends" with the U.S. women's soccer team now, after a mix-up back in 2012.

RG3 was out at Mastro's Steakhouse last night when he told us he's thrilled for Team USA -- especially since he's become tight with stars like Alex Morgan, Tobin Heath and Sydney Leroux.

So, what's the embarrassing part? Back in '12, he THOUGHT he met Alex Morgan at an event ... and even went to Twitter to thank her for being so nice.

Problem is ... it wasn't Alex Morgan -- who responded on Twitter, "I think u met @TobinHeath today but hopefully I'll see u around. Good luck in the draft!"

Oops.

The good news ... RG, Alex and Tobin all joked about it on social media -- and RG3 says they're all friends now. So, the public humiliation paid off!