Jessica Biel's face will go scarlet when she hears about this!
The new Us Weekly reveals that Justin Timberlake spent the night of Sept. 14 with another Hollywood beauty: Single-again Scarlett Johansson, his smoking-hot costar in his 2007 "What Goes Around Comes Around" video.
Timberlake, 30, and Johansson, 26, were "hardcore flirting" during a raucous evening at NYC hotspot 1Oak, a witness tells Us. "Other guys were trying to talk with Scarlett, but she was only focused on Justin."
The duo literally partied until dawn –leaving at 5:30 a.m. and getting pizza next door, the source says. The one-on-one party continued just a few hours after the A-listers closed down 1Oak — when Timberlake showed up at the Iron Man 2 actress' midtown penthhouse apartment.
Greeting the doorman and introducing himself as "Justin," Timberlake "wasn't even low-key" about his visit, another witness noted. (Reps for both stars deny the visit took place.)
"They've hooked up several times over the years," a pal confirms of the pair. But Timberlake just got back together with longtime love Biel, 29, merely a month ago.
"For the moment," another insider says, "she's trusting him."
For more on Timberlake's latest betrayal — and what's going on with Johansson and Kieran Culkin — pick up the new Us Weekly, out now!
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!