Marc Anthony had an interesting crew inside his birthday celebration at a Dolphins game last night -- including Fergie, Sean Kingston and, most surprising of all, Will Smith.

Marc and Will made a deliberate display of camaraderie on Monday amid rumors that Anthony had an affair with Smith's wife, Jada -- rumors both have adamantly denied.

Marc and his ex, Jennifer Lopez, are part owners of the football team -- as well as Fergie, who sang the National Anthem before the game.

Fergie's husband, Josh Duhamel, also attended the bash, as well as Pitbull, who sings with Anthony on his latest single "Rain Over Me."

Anthony turns 43 on Friday.