Justin Timberlake throws 'Suit & Tie'-themed birthday bash for Timbaland

Justin Timberlake and Jay-Z are collaborating outside the studio, too.

The twosome hit up a private suit-and-tie-themed 41st birthday party on Thursday night for Timbaland, who produced Timberlake's new single "Suit & Tie," featuring Jay-Z.

The bash doubled as a second anniversary party for Timberlake's Southern Hospitality, a Hell's Kitchen barbecue joint.

Jay-Z and Timberlake partied until the early morning with their wives, Beyoncé and Jessica Biel, along with rapper Missy Elliott, "Django Unchained" star Jamie Foxx and Chelsea Clinton, according to a witness.

With music supplied by DJ Ani Quinn, partygoers toasted to Timbaland with Armand de Brignac Champagne and danced in a pop-up nightclub, where Jay-Z, Beyoncé, Timbaland and Foxx held court. Meanwhile, Timberlake and Biel were found at a casino that was set up to raise money for Timbaland's charity, the Always Believing Foundation.