The comic star filed for divorce from his wife Katy Perry just a few weeks ago but has already returned to his womanising ways and is seeing more than one girl, according to Us Weekly magazine.
Katy has been told that her estranged husband - who has previously been treated for sex addiction and substance abuse issues - has moved on from their marriage by her pals.
A source said: "She discovered through her friends. One of the women told a friend of hers and it got back to Katy."
It's not only Russell's foray back into the singles' scene which has upset Katy, 27. The 36-year-old actor has also allegedly been bad-mouthing his wife to his conquests.
The source added: "He's spoken terribly about Katy to them. Russell told (one girl) he wanted her to move in with him after the divorce is final."
The 'Rock of Ages' star filed divorce papers on December 30 after he and the 'Firework' singer spent Christmas apart. Before he started his relationship with Katy, Russell - who married the pop star in India in October 2010 - was renowned for his womanising and had bedded a string of beauties including Kate Moss, Australian actress Teresa Palmer and allegedly Holly Madison.