By day, he's Justin Gatlin. By race, he's alter ego 'J Gat'

Justin Gatlin swears he's not as bad as he's made out to be. He calls his alter ego ''J Gat.'' And that's someone you don't want to mess with. Before a race,

Justin Gatlin swears he's not as bad as he's made out to be.

He calls his alter ego ''J Gat.'' And that's someone you don't want to mess with.

Before a race, the mild-mannered American sprinter says he transforms himself into the feisty guy named ''J Gat,'' a nickname he's given to a version of himself that wants to take over the world from archrival Usain Bolt. Their rivalry heading into the Rio de Janeiro Olympics has sometimes been portrayed as ''Good vs. Evil'' given Gatlin's doping history.

''I don't accept myself being the bad guy,'' Gatlin said. ''I'm a winner. I'm a competitor. I'm a brave person. I'm a good person. I know this about myself and I have to act like that.''

''J Gat'' to the rescue. He runs with fury and looks ''mean and intimidating'' when caught on camera after races.

That's not the real Justin Gatlin.

''Justin has only gotten as far as starting line. After the gun goes off, it's never Justin. It's always as `J Gat,''' Gatlin said. ''I'm a whole different person away from track.''

To illustrate that, Gatlin is making a documentary. The 34-year-old will have a film crew trailing him around at the Prefontaine Classic this weekend in Eugene, Oregon, to record his every move.

One caveat: Stay out of the way of ''J Gat.'' You wouldn't like him when he's angry. (Case in point: gesturing toward a heckler who was bothering his mother in the stands during the awards ceremony at worlds last summer).

''A lot of athletes get consumed by the Hollywood lights,'' said Gatlin, who will face a 100-meter field at Pre that includes Americans Tyson Gay and Mike Rodgers, along with Asafa Powell of Jamaica. ''I'm like, `We can make this story, but I have to still do my job. We have to coexist together. I can't give you my undivided attention and go off and start losing races.'''

There's no working title yet for the film or date when it will air. And no subject is out of bounds, including his doping past. The 2004 Olympic 100-meter gold medalist tested positive for excessive testosterone in 2006, was reinstated from his ban on July 24, 2010, and returned to capture bronze at the London Games two years later.

He's been one of Bolt's biggest threats ever since.

''The theme of (the movie) is basically my journey,'' Gatlin said.

Gatlin recently showed the roughly 90-second trailer to his 6-year-old son, whose first words were: ''Play it again, dad.''

''That was the cutest thing ever,'' Gatlin said. ''He's like, `I have to be faster than a cheetah to keep up with you, dad.' That makes me proud.''

The trailer shows flashes of Gatlin stretching, lifting weights and sprinting. In one scene, he said: ''If I could do this forever, I would. I love the pain I get from training. I know that it's a pain of growth. Inside, I'm infinity.''

Gatlin said he'll race at least through the 2020 Tokyo Olympics so his son could be there.

''I'd like to give that to him as a gift,'' Gatlin said. ''Even if I don't win in 2020, just to be able to be on the team.''

Gatlin's times in the 100 have been slower this season, running 9.94 seconds so far compared with 9.74 this time a year ago.

All by design.

He's treating the early season races more like rounds so he can work on his form. Gatlin believes he has the speed to keep up with Bolt, but needs to execute his style of race.

That didn't happen in Beijing at the world championships last summer. Gatlin was a slight favorite in the 100 meters given that Bolt wasn't exactly race sharp. Gatlin was neck-and-neck with the Jamaican, but over-strided with about 15 meters left. Gatlin went into his lean too early, paving the way for Bolt to capture gold yet again.

''It's all a process,'' Gatlin said. ''Sometimes, processes are rewarding and sometimes processes are painful.''

Before a 100-meter showdown with Bolt can occur in Rio de Janeiro, Gatlin has to make Team USA at the Olympic Trials in July. It's not an easy task with sprinters such as Gay, Rodgers, Trayvon Bromell and Gatlin contending for three spots. Gatlin also will try to earn a place in the 200 meters.

To assist him, he will summon ''J Gat.''

''Very rarely will you find an athlete that calls me Justin,'' Gatlin said. ''It's always `J Gat.' Justin has never run a race.''