Justin Bieber Jams To Ludacris' 'Baby' Performance At Sports Illustrated Party

It's been more than 16 years since it came out, but Justin Bieber and Ludacris still got "Baby" fever ... with the pop superstar vibing to the rapper's performance of their hit song at a Super Bowl bash on Saturday.

Luda and The Chainsmokers headlined the "Sports Illustrated The Party" festivities at the Cow Palace Arena on Saturday ... making sure the folks in attendance got all the bangers leading up to the Big Game.

Even though Luda can stuff a setlist with his own classics, he also gave the crowd his verse on the 2010 track with JB ... and the "Yukon" crooner himself was among the thousands dancing along ... he was spotted waving his arms around with a cigar in his hand.

Once the track was over, the two had a special moment together ... with Bieber popping on stage to give his buddy a hug.

On top of JB and his wife, Hailey ... Russell Wilson and Ciara, Rob Gronkowski, George Pickens, Kevin Hart and a bunch more celebs rolled through for the night of fun as well ... with DJ Irie and Xandra providing tunes before Ludacris and The Chainsmokers took over.

S.I. doesn't mess around when it comes to throwing events -- some tix cost $1,300 ... which included luxurious experiences like VIP lounges, open bar, gourmet snacks and more.

We're told the venue was packed with attendees soaking in all the organizers had to offer.

Luda hopped on stage around 11:30 ... and the DJ duo closed out the night around an hour later with a packed set.

If it's JB-approved ... we take it everyone left satisfied.

Pretty much the entire Bay Area was a rave on Saturday night ... 'cause Dom Dolla also hopped on the 1s and 2s for a massive crowd at a show in San Jose.