Spotted: Scarlett Johansson and 'Hangover' Star Justin Bartha

Scarlett Johansson could be on her way back to the dating scene less than a year after her divorce with Ryan Reynolds after witnesses saw her getting cozy with Justin Bartha from The Hangover.

The rumors come a month after the actress finished an alleged brief dating period with Sean Penn. According to the New York Post Johansson and Bartha were spotted together backstage of the off-Broadway show, All New People, in which Bartha stars.

Later the two were seen at the post-show dinner at Café Un, Deux, Trois where witnesses told the New York Post that the two were completely engrossed in one another, sitting side by side at the 15-people dinner and talking to one another all night.

Meanwhile Johansson's ex-husband Ryan Reynolds is rumored to be dating 34-year-old Oscar winning actress Charlize Theron. One source told the US Weekly that the couple were exclusive but it is very 'hush hush' and Theron is not the kind of women to be exhibiting her relationship on the red carpet.

If things were not confusing enough, PEOPLE Magazine reported last Saturday that Johansson and ex-husband Reynolds were seen having dinner together at Little Dom's Restaurant in L.A.

They were leaning in closely to each other when talking, a source at the restaurant told PEOPLE. They were being flirty.