As reports fly that Reese Witherspoon has a new flame in CAA agent Jim Toth, Jake Gyllenhaal has suddenly become Mr. Popularity with the ladies.

First up: his hang-time last weekend with G4 hottie Olivia Munn, who was most recently linked with “Star Trek” captain Chris Pine. E! News reports Gyllenhaal chitchatted with the dark-haired looker during Saturday’s Night Before Oscars bash at the Beverly Hills Hotel after being introduced by mutual pal Jamie Foxx (huh, random).

“Once they met, Jake didn’t leave her side the entire night,” relays a spy. “They looked like they were having fun, both laughing a lot.”

The pair later moved their tête-à-tête to Soho House, but, a mole downplays, “nothing happened romantically.” Still, they supposedly exchanged digits with an eye toward getting together “soon.”

Meanwhile, armchair matchmakers are attempting to will a relationship between Gyllenhaal and his Oscar night co-presenter, Rachel McAdams, into existence.

Sure, they looked adorable onstage, but is there potential for a love connection, or is this just a case of

the public casting around for a new dream couple who we can dub with an annoying nickname (we’re partial to McGyllenhaal)?

The evidence remains circumstantial, at best: During a backstage interview with Oprah regular Nate Berkus, the buzz cut-sporting star of the forthcoming big-budget flick “Prince of Persia” held the actress’s pink purse. Also, he introduced her to a pal by joking, “This is Rachel McAdams, she’s the mother of my child!”

Life & Style adds that McAdams had her sister switch seats in the audience so she could sit next to

Gyllenhaal and (fresh breath alert!) popped a mint in her mouth while sharing a laugh with him.

Like we said, circumstantial at best.

Meanwhile, is Rachel’s ex-boyfriend and “Notebook” leading man, Ryan Gosling, moving on? Head over to the Romance Report for more on that …