FILE PHOTO: Justin Gatlin of the U.S. celebrates after winning the "Mano a Mano" challenge, a 100-meter race, at the Brazilian Jockey Club in Rio de Janeiro, Brazil October 1, 2017. REUTERS/Bruno Kelly

CAPE TOWN (Reuters) - World 100-metre champion Justin Gatlin will race over a new distance next month at the inaugural Athletics South Africa (ASA) Athletix Grand Prix series meet in Pretoria.

U.S. sprinter Gatlin, 35, will compete in the 150-metre sprint in what will also be his first competitive run of 2018.

“I have obviously done 150s in training‚ but have never raced over that distance before‚” Gatlin said in a statement released by ASA on Thursday.

“It will be interesting to see how I do. It is also my first race of the season‚ which adds to the excitement for me.”

The sprinter sacked coach Dennis Mitchell in December after doping allegations were made against Mitchell, who like Gatlin was previously banned for doping. Gatlin is now back with former U.S. Olympic and national team coach Brooks Johnson, who trained the sprinter in 2010-11.

In a statement in December to Britain’s Daily Telegraph, which made the allegations against him, Mitchell said: “I never suggested in any way that any of my current athletes used any banned substances or that I was familiar with training any of my current athletes with those substances.”

The Athletics Integrity Unit and the U.S. Anti-Doping Agency (USADA) have both said they are investigating the allegations.