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After hitting the Grammys solo, Justin Timberlake hooked up with girlfriend Jessica Biel for some partying and PDA.

The couple hit Grammy winners Kings of Leon's exclusive post-party held at Teddy's, where they held hands and stayed by each other's side all night.

"They were dancing, singing, laughing," says a source, who adds that JT even had a dance-off with a friend.

Newlyweds Scarlett Johansson and Ryan Reynolds also attended the bash, sponsored by Belvedere IX. The two were spotted kissing at the soiree, where Ryan, appropriately enough, sipped Belvedere IX-and-cranberry cocktails.

Also attending the party: Katy Perry, Kid Rock and Slash.