Demi Lovato earns jiu-jitsu blue belt in record time

Demi Lovato has shocked MMA superstars and training mates Chuck Liddell and Randy Couture by earning her Brazilian jiu-jitsu blue belt in record time.

The Cool for the Summer hitmaker has been quietly working hard at Jay Glazer's Unbreakable Gym in Los Angeles, California for the past year, and her diligence has paid off.

Gym owner Jay was so impressed with her achievement in knocking a year off the usual two-year process of graduating from basic white belt status to blue, that he flew to L.A. to present the belt personally to the singer on Monday (28Aug17).

He also tweeted about Demi's big kicker of a feat, writing: "I'm more proud of the work (she) puts in with nobody watching than i (sic) am what she does with the world watching. Congrats on achieving your blue belt today in #bjj (Brazilian jiu-jitsu) YOU put the grind in!"

The presentation follows Demi's showstopping performance of the U.S. national anthem before Floyd Mayweather and Conor McGregor's big boxing fight on Saturday night (26Aug17) in Las Vegas.

The star, who also performed her hit Sorry Not Sorry at the MTV Video Music Awards (VMAs) on Sunday (27Aug17), is a huge mixed martial arts fan and she previously dated mixed martial arts fighter Guilherme Vasconcelos and Ultimate Fighting Championship star Luke Rockhold.

The 25-year-old has become a real gym rat in the past year, revealing she fell hard for jiu-jitsu on day one: "I'm kind of in love with it... I've been doing it for about a year and it has just been so much fun, I have a new found passion for it and I really enjoy it.

The Cool for the Summer hitmaker has also gained a greater control of her diet and eating habits thanks to the discipline instilled in her through mixed martial arts.