Selena Gomez gave advice to Jeff Ross on roasting Justin Bieber.

When asked if he researches dirt about the celebrities he roasts, Jeff told The Huffington Post newspaper: "I did actually, I even talked to Selena Gomez.

"I ran into her and asked her for advice on roasting the Biebs, and she said, 'Tell the truth. That always worked for me.'"

The 22-year-old singer - who had been dating the 21-year-old pop star on and off for four years until they called it quits in October last year - was also the subject of a cruel joke during the roast.

In the show, Jeff said: "Selena Gomez wanted to be here but she's dating men now.

"Is it true you dumped her because she grew a moustache before you?

Selena Gomez had sex with [you]... proving Mexicans will do the disgusting jobs Americans just won't do."

During the roast, Justin also took the opportunity to apologise for some of his behaviour over the last couple of years.

He said: "I lost some of my best qualities. I'm looking forward to being someone to be proud of.

"Someone close to me once said how you rise from a fall is how you are truly defined as a man."