The 76-year-old showbiz legend has fallen hard for the hunky “Noah” star, 50, after the two hit it off filming the upcoming flick “Fathers & Daughters.”

“Jane is gaga over Russell,” revealed an insider.

“She thinks he’s the total package – smart, with a good sense of humor, macho and ruggedly handsome. She can’t stop raving about him.

“When she wrapped up her scenes, she got his phone number and email address. She’s been sending him flirty messages and suggesting they get together once their schedules allow.

“But Jane’s boyfriend (Richard Perry) is none too amused. He’s told Jane to knock it off.”

Jane and music producer Perry, 71, have been together since 2009, and she recently went public on her  blog about his courageous battle with Parkinson’s disease.

“After dealing with Richard’s health woes, hanging with a guy as virile as Russell must have been a fun distraction for her,” said the insider.

In their movie drama, which just finished filming, Jane plays a literary agent and Russell is a famous author. Amanda Seyfried co-stars as Russell’s daughter. Ironically, as The ENQUIRER revealed last year, the Aussie heartthrob tried unsuccessfully to woo Amanda after they filmed “Les Miserables.”

The hot-tempered father of two has been on the prowl since splitting from his wife Danielle Spencer in 2012 after nine years of marriage.

Although Russell struck out with Amanda, Fonda recently revealed on her blog how excited she was to meet him on their film set.

“I didn’t know what to expect and was excited and nervous,” she wrote. “Was he going to be standoffish? Moody? Hard to work with? I needn’t have worried. First of all, he moved me to tears on a number of occasions during our scenes together…

“He was friendly, present and smart. OMG the man is smart and thoughtful.”

Jane even posted pictures of the two with arms around each other.

“Jane swears to Richard that her interest in Russell is purely innocent,” said the source. “But with friends, she refers to him as ‘my dream man’ and says if she were single, she’d make a major play for him.”