Credit: Jason Merritt/Getty; Steve Granitz/; Jon Kopaloff/FilmMagic

He didn't win best actor, but Jake Gyllenhaal took the top prize for flirting the night of the Jan. 16 Golden Globe Awards.

"He was talking to so many girls!" a witness tells the new Us Weekly of the actor, 30, who ended his whirlwind romance with Taylor Swift, 21, just two weeks earlier.

"At CAA's after–party, Jake macked on Maria Menounos -- and he was definitely trying with Scarlett Johansson!"

The star -- who brought ex Jenny Lewis, 35, to the show (he dated the singer in 2001) -- also chatted up Mila Kunis, 27, that night.

Says the source, "Jake seemed interested, but he's not her type."

Later, he hit the Chateau Marmont and got close to Brokeback Mountain costar Michelle Williams, 30. Says an insider, "His hand was on her knee!"