Jack Osbourne had a reason to celebrate his 25th birthday two days early: his new girlfriend, Sarah McNeilly, was by his side. The American fashion model accompanied Jack to the 5th anniversary of TAO restaurant and nightclub in Las Vegas on Nov. 6, an insider tells Life & Style. "Sarah was there as Jack's date," the insider says. "He took her to Vegas to celebrate his birthday with him."

The reality star, who turns 25 today, has also been linked to model Kimberly Stewart. But it seems as though Sarah has won his heart. "TAO presented Jack with a birthday cake, and Sarah was by his side when he blew out the candles," continues the insider. "They're very much on, full speed ahead. They seem super into each other! Both seem very happy."

And a very happy birthday to you, Jack!

Photo Credit: Denise Truscello