Richie Sambora: I'm the Best Wedding Singer in Bon Jovi ... Sorry, Jon

Richie Sambora just beat Jon Bon Jovi in a game of wedding singer.

We just got this video of former JBJ lead guitarist Richie strumming the band's classic, "Livin' On a Prayer" at his nephew Shane Ahern's L.A. wedding. You might think a rocker of Sambora's caliber would shy away from this sorta thing ... but he's sooo into it.

We're told the DJ provided the guitar, but the whole thing was unrehearsed. The woman singing with Sambora is Orianthi, who's currently touring with him.

You might recall Jon had a similar sitch while attending a wedding last week -- but unlike Richie, he had to be strongly nudged into belting out the same tune.

Check out both vids ... we're giving Sambora a narrow victory, based purely on enthusiasm.