Usher has opened up about the trials of being famous in defence of his protégé Justin Bieber.

The Yeah! hitmaker scooped the favourite male artist in the soul/R&B category at the American Music Awards in Los Angeles on Sunday night.

Backstage he was asked if he had any advice for 18-year-old Justin, whose relationship with Selena Gomez has been highly scrutinised since their reported break-up two weeks ago.

Usher suggested critics hold their tongues because few could understand the kind of pressure stars are under.

“The truth is on one can ever understand the reality of the life we live,” he told US television news programme Extra.

“We are humans, humans have frailties… humans have ups and downs,” he said.

Usher opened the AMAs with a remix of his hits including Numb, Climax and Can’t Stop, Won’t Stop, joined by a team of backing dancers.

Justin later took the stage for a high energy performance of Beauty and a Beat with Nicki Minaj.

The Baby hitmaker was the toast of the evening, scooping awards for artist of the year, favourite pop/rock male artist and favourite pop/rock album.

Rumours continue to swirl over his relationship with Selena.

The former Disney star did not attend the AMAs but was pictured holding Justin’s hand at an after-party. The event came days after it was reported the couple called it quits for good after a blow-up fight at a Los Angeles restaurant.