According to the Daily Star Sunday, N-Duz star Fazer was caught “outrageously” flirting with model Hannah Louise Borg.
Hannah is quoted by the tabloid as boasting: “I fancy him but I’ve got competition.”
The newspaper claims that the pair hooked up last November, as Tulisa was working on The X Factor, but the details of their fling have only just come to light.
Tulisa and Fazer, real name Richard Rawson., ended their 18-month relationship in January.
The feisty singer had previously admitted that she didn’t stand for "any s***e" when it came to cheating boyfriends.
She said: “I don’t stand for any s***e...I’m selfish. I’m very stubborn. I never back down and I’m possessive.”
Hannah meanwhile revealed she was going to sell her story to a magazine.
She said: “I don’t want to talk about it. I’m doing an interview with a mag and that’s all.”