LONDON, England (AP) — All anyone’s talking about ahead of the men’s 100 meters is the showdown between Olympic champion Usain Bolt and world champion Yohan Blake, a pair of Jamaicans who train together.

As the premier track and field event of the London Games gets started with opening heats Saturday, it seems everyone has an opinion about who’s going to win — and the answers tend to be Bolt or Blake.

There are other contenders. There’s the third Jamaican in the field, Asafa Powell. There’s US-record holder Tyson Gay, surgically repaired hip and all. And there even is another past Olympic champion, Justin Gatlin of the US, who walked off the stage in Athens eight years ago with the 100 gold.

But in 2006, Gatlin tested positive for excessive testosterone, leading to a four-year ban that prevented him from defending his title in Beijing.

Now 30, his prime years perhaps in the past, Gatlin has picked up his career. And guess what? He still believes he has a shot to reclaim his crown, even if he readily admits it’s a long shot.

“There are other guys out there who have the upper hand on me since I’ve been gone for four years,” said Gatlin, who won the 100 at the US trials in June. “It’s going to be an uphill fight for me to claw to the top.”

Just as tough has been enduring all the negative talk, which goes something like this: Once a doper, always a doper.

He knows he can’t change that perception. He’s stopped trying.

“Look, I’ve turned the page, but it’s a part of my book,” he said. “I can never close the door on the past four years and say never I’ll never look at it, because that’s where a lot of my strengths have come from and a lot of my bravery.”

During his ban from the sport, Gatlin found himself relying on unemployment checks to make ends meet.

“Going through the struggle I went through not only humbled me in my lifestyle but strengthened me as a person,” he said. “I was able to turn into a man and understand what it is to not know where your income comes from. Because everything just pretty much imploded.”

Steadily, he’s picking up the pieces.

He’s also regaining the form that made him an Olympic champion. He’s shed weight, dropping about 20 pounds over the last year to get down to a little more than 180, and changed coaches, switching to Dennis Mitchell.

“I remember reading a blog site, where one blogger said I looked like a professional wrestler on the track,” Gatlin said. “I was that big.”

The challenge now for Gatlin — and for everyone else in the race — is finding a way to get past the 6-foot-5 Bolt, whose height helps him get to the finish line with fewer steps.

“He’s going to cover more ground,” the 6-1 Gatlin said. “So you’re going to have to compensate somewhere else, being with strength or turnover. But Tyson beat him (in 2010), so that gives a lot of other runners, who are brave to go out there, confidence.”

More recently, Blake beat Bolt, too. That happened at the Jamaican trials.

“I don’t really want to say he’s vulnerable,” Gay said. “He’s the only guy who’s been where we haven’t been. I think he still has to be one of the favorites. He’s the champion and knows what it takes to compete on this level.”

Sure does.

Bolt, after all, won the 100 and 200 at the Beijing Olympics, both in record time. He still owns both marks, including the 9.58 he ran in the 100 at the 2009 world championships.

Not everyone likes his chances in London, though.

Maurice Greene, the 2000 Olympic champion in the 100, thinks Blake is simply too strong right now.

“Technically, he’s better,” Greene said. “You win and lose through your technique, and Usain has been having technical problems for the last two years. He hasn’t fixed it since then. … I don’t see him fixing it now. You have to go with (Blake).”

Gatlin also pictures himself in the mix for a medal.

“You always see these epic photos or short clips, where the whole stadium is dark and dim and then it goes really quiet,” Gatlin said. “You see eight guys in the starting blocks, (the gun goes off), and the stadium lights up like a night’s sky with photography. … It’s so special. I’m so glad I get to be a part of this now.”