Top TV producer: 'Ariana Grande is the ultimate professional'

Top TV producer Bill Bracken has defended Ariana Grande from reports of bad and difficult diva behavior, insisting she was a consummate professional when she agreed to record a one-off duet with Canadian singer Michael Buble for his fourth annual Christmas concert special this December (14).

The Home hitmaker has turned his love of all things festive into an annual TV treat for fans since 2011, and this season, he will be teaming up with pop star Grande to perform an as-yet-unannounced collaboration.

The Problem singer has faced a public backlash in recent weeks following a series of stories about her alleged "diva" behavior, with reports suggesting she axed her Australian promotional tour because she was unhappy with a photoshoot, while a group of fans accused of being rude and stand-offish at a meet-and-greet session.

Grande previously brushed off the claims, insisting the "diva" label is actually a compliment, and now Bracken has spoken out about the rumors, admitting he has nothing but compliments about the 21 year old.

He tells the New York Post, "There's no bigger young star today than Ariana Grande. We've had a good relationship with her and flew to Vancouver, where she was performing, to organize this. She gets a bad rap as being difficult. She's not. She's great.

"(She) came on time, brought her own costumes - white short skirt and top for the solo, red dress for the duet - (she) was prepared, rehearsed. Two songs with Buble... performed 10 minutes after arriving - and out in an hour."

Michael Buble's Christmas special will air in America on 17 December (14). It will also feature an appearance by veteran entertainer Barbra Streisand, who recently recruited Buble to sing with her on her star-studded duets album, Partners.