It was the best day of his life, but Justin Timberlake wasn't feeling one hundred percent when he became a married man October 19.
The insider adds that the couple's intimate group of pals spent a good amount of time at the hotel bar. "They had a big night at the bar where everyone went crazy -- but Justin wasn't feeling great," the insider tells Us.
Even if the under-the-weather "SexyBack" singer didn't party as hard as he might have, "Justin was in a good mood," the source says. "He had fun."
"The biggest surprise to everyone was that it was such a small group and not star-studded," notes the source of the destination wedding, where the few celebs in attendance included mega-producer Timbaland, Timberlake's "D**k in a Box" costar Andy Samberg, Biel's 7th Heaven pal Beverley Mitchell and music manager Johnny Wright. Pre-wedding festivities also included a beachfront bash (with fireworks!) at Cala Masciola and cultural activities, too.
"Justin stayed with his family most of the time," The source says. "They had a schedule of everything for guests to do throughout the weekend."
For her walk down the aisle, Biel, 30, wore a pink-and-white gown -- reportedly designed by Giambattista Valli with a "princess-like silhouette" -- which she changed out of for the reception.
Despite not feeling so hot, Timberlake pushed through to serenade his bride at the reception. "Justin performed one song at the wedding," a source reveals. "It's a new one that he hasn't released yet. He dedicated it to Jessica."