Sofia Vergara Wardrobe Malfunction -- BREAST New Year's Eve Fight Ever!!!

Sofia Vergara's strapless gown lost a New Year's Eve fight -- but every guy in the party won when one of her glorious boobs popped out of the dress in the middle of the scuffle.

Sofia and her fiance Nick Loeb were partying inside the Miami nightclub Story when the pushing and shoving started -- reportedly with some people at a table next to theirs.

Sofia jumped in to try to break up the fight, got bumped to the ground ... and that's when her gown -- which was already holding on for dear life (below) -- released its precious cargo.

The "Modern Family" star wasn't hurt in the brief melee ... but Nick reportedly suffered a few bruises while struggling with security.