Usher has "quit all sugar and alcohol" ahead of his Super Bowl performance.
The 'Yeah!' singer is set to headline the half-time show at the NFL showpiece game next month and he's determined to be in the best shape possible in order to give the performance of his life.
A source told the Sunday Mirror newspaper's No Filter column: "The Super Bowl has always been on Usher's bucket list and he wants to be in the best shape to give the performance of his life to the 100 million-plus people watching.
"He has quit all sugar and alcohol and is rehearsing endlessly."
Usher - who joined Black Eyed Peas on stage during their 2011 Super Bowl gig - previously admitted he had been waiting some time to get the call to headline the sporting show.
He told Zane Lowe on Apple Music 1: "I think being able to see performances from artists like Michael [Jackson], you know, eventually Prince, and then even more modern-day artists... I was like, 'Man, at some point I need to get a call with what's going on now.'
"But I'm really happy that I'm joining that short list of legacy artists from my genre who deserve this moment.
"And I'm really happy that Jay-Z and also Roc Nation really put thought into making certain that they could bring to the world this kind of experience. It is definitely going to be a moment to remember."
The 45-year-old singer has also enlisted the services of his 14-year-old son Naviyd to be his "musical director" for the show, which takes place at Las Vegas' Allegiant Stadium on 11 February.
Speaking on 'Today With Hoda and Jenna', he spilled: "The greatest list I received is actually from my son, Naviyd. He is my musical director.
"He has given me a curation of how much time in addition to the songs."
