Christina Aguilera's son is not impressed with her singing.

The 29-year-old pop star loves to sing lullabies to two-year-old Max - whose father is her estranged husband Jordan Bratman - though she admits she has to alter her performing style when she is at home to make the youngster happy, though he is still often left underwhelmed by her efforts.

Christina said: "I tone it down when I'm singing lullabies to him, I don't sing 'Lady Marmalade'. I definitely don't bring out the pipes for lullabies.

"He does have a mind of his own though. Sometimes he'll be my worst critic and he'll go 'No mommy not 'Twinkle Twinkle', not tonight. Not that one, sing 'Wheels on the Bus' instead.' "

Although Christina's son is not impressed with her vocal talents, she revealed she knew she wanted to be a singer when she was Max's age.

She explained to US TV talk show host Conan O'Brien: "I was in diapers when I knew that I wanted to be a singer, as a little girl I would just open my mouth and sound would come out. I would throw a towel on the floor as my stage and use a shampoo bottle for my microphone."