Justin Timberlake enjoys Rat Pack-themed bachelor party in Vegas

Justin Timberlake said adieu to his single life on Thursday in Las Vegas, as the actor-singer was spotted with a crew of friends celebrating what appeared to be his bachelor party.

Kicking off at the Wynn’s Sinatra Restaurant, JT and a group of about 25 guys decked out in Rat Pack-esque suits for a meal, according to a Ministry source — more than appropriate as the joint is described as a culinary tribute to Ol’ Blue Eyes.

Heading to the hotel’s Surrender nightclub just before midnight, Timberlake and company climbed out of their formal wear and into bathing suits, splashing in a private infinity pool within a reserved cabana.

Timberlake sipped on 901 tequila, his own brand, while his party opted for vodka and Red Bull. The group took shots and enjoyed people watching. Frequent collaborator Timbaland, in town with wife Monique, also stopped by to wish Justin well.

Timberlake is engaged to marry actress Jessica Biel. He popped the question in Aspen, Colo., over the 2011 holidays.

“I don’t think our marriage will change anything,” Biel has said of the milestone. “It’s just a challenge to balance privacy, family and work,

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