Nikki Glaser has been warned off making jokes about "America's sweetheart" Julia Roberts at the Golden Globe Awards

Speaking on CBS Mornings, she said: "I'm trying out my monologue around L.A., at the clubs here, and just even any joke about Julia Roberts, they are not there for.

"You cannot make fun of America's Sweetheart. So, whatever I end up saying about her, that is the most fine-tuned joke that I've worked on so hard, because it is very delicate."

Nikki admitted the crowd were booing so much she thought Julia herself may have been in the audience when she was trying out her Globes monologue.

She added: "They were booing, and I was like, 'Is she here?' It's insane."

Nikki, 41, has been forced to take a "different approach" this year because several iconic actors, including Julia, Leonardo DiCaprio and Sean Penn, are up for awards, and she feels it's harder to poke fun at them compared to stars who are younger than her.

She added: "I am a huge fan of these people.

"It's easy for me to take down the newer batch of actresses and actors who are younger than me. It's like, 'OK, I can make fun of you. I'm like a veteran.'

"But when it's people that I grew up admiring, it's a different approach this year.

"You have to be very delicate about making jokes that aren't going to ruin anyone's night.

"But you also want to give the people at home something to laugh at, and you want to poke fun at the people that they're dying for you to make fun of. People at home want you to make fun of the A-listers."

Nikki's comments come after she pledged not to tell predictable jokes about DiCaprio at the Golden Globes this year.

She told People magazine: "I don't think I'm going to go with the Leo jokes we've heard 25 times. I think we've all heard that - that's been done enough."