Madonna is dating her 26-year-old backup dancer Timor Steffens.
The 55-year-old singer reportedly attracted disapproving glances when she brought her new Dutch beau to designer Rudolph Valentino's private New Year's Eve Party in Gstaad, Switzerland.
She split from her 25-year-old boyfriend of three years, Brahim Zaibat, recently.
A fellow party guest told gossip website RadarOnline.com: "The chemistry between Madonna and Timor was pretty intense.
"Some people at the party were whispering about how Madonna had just broken up with her ex, and now she's already with a new guy.
"It's that kind of crowd. Plus, you can't really ignore the fact that Timor is so much younger than Madonna. I mean, he's basically a replacement for her ex. He looks just like Brahim."
But the Hung Up hitmaker wasn't upset by the negative attention.
The couple bonded after working on a dance project together and Timor is already close to her younger children, Rocco, 13, Mercy James, seven, and David Banda, eight.
The source said: "Madonna was even hinting to people that one of the reasons she likes Timor so much is because he's a natural with her children.
"She isn't really the type to come out and say something like that, but it was obvious. She had a little smile on her face whenever she watched Timor goofing around with Rocco and the other kids."