Jennifer Lopez was left red-faced when she forgot the name of American Idol mentor Steven Van Zandt live on stage.

Steven, 65, a longtime guitarist with Bruce Springsteen and a former castmember of HBO show The Sopranos was invited by in-house mentor and Big Machine Records label head Scott Borchetta to mentor the remaining top five American Idol contestants through a theme of classic rock songs on Thursday night's show (24Mar16).

When it came to contestant Mackenzie Bourg's take on Cheap Trick's I Want You To Want Me, Jennifer, 46, said he “Mackenzied it” but wasn’t sure if she really loved it, saying the performance “Wasn’t as exciting as I wanted it to be.”

The Booty singer then added insult to injury when she couldn't recall Steven's name, looking to fellow judge Keith Urban for help.

"I would have liked to have heard what you did originally before...uh, uh... mentor?" she said.

Country music star Keith deadpanned "Cheap Trick" before colleague Harry Connick Jr. then jumped in telling her, "Steven."

The faux pas evoked the ire of Steven's wife Maureen, who quickly took to Twitter to express her disappointment at Jennifer's misstep.

"Really @JLo needs to f**k off," she wrote. But actress Maureen, 64, didn't stop there continuing that she felt Jennifer "shows how little homework she does. Or how little she retains. And Stevie did not do that arrangement."

She concluded by writing, "she knows nothing about the rock world. And is a music judge?"

Maureen has since removed some of the tweets from her feed.