(CNN) He's targeting a record-equaling sixth Kentucky Derby win, but champion trainer Bob Baffert believes the Churchill Downs showpiece is "wide open" this year.

The 66-year-old saddles favorite Game Winner -- installed at the head of the market after the withdrawal of Omaha Beach -- alongside Roadster and Improbable.

But the Arizona handler, who won the Derby with Justify last year en route to a second Triple Crown in four years after the success of American Pharoah, is unsure which of his trio is the most likely to succeed.

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"I'm not armed like I was last year," Baffert told Aly Vance for CNN's Winning Post show Thursday.

"Game Winner was a champion two-year-old, but I don't know how the weather is going to affect him -- he comes from off the pace and might have some traffic problems.

"I love Roadster, but he's got to prove something, he's lightly raced; and Improbable, if he doesn't get too excited -- they have to handle crowds -- the way he's been training he loves this track but he needs to break [out of the stalls].

"One day I like one and then I'll change my mind. I think Improbable, we don't know if he'll get the mile-and-a-quarter -- but that Game Winner he's tough. I don't know how good Roadster is. I don't care which one wins as long as one does.

"I think this is a tough Derby, it's wide open. There's really nice horses in there."

The leading contender outside of the Baffert trio is Maximum Security, trained by Jason Servis, while Haikal's late withdrawal with a hoof abscess has reduced the field to 19.

Photos: The Derby returns to Churchill Downs The Kentucky Derby, first run in 1875, is the first leg of the American Triple Crown and a sporting and cultural icon in the US. It is for three-year-old thoroughbreds and is run over a mile and a quarter at Churchill Downs. Hide Caption 1 of 16 Photos: The Derby returns to Churchill Downs More than 150,000 racegoers packed out Churchill Downs in Louisville for last year's Kentucky Derby , one of the best-loved events in the racing calendar. Hide Caption 2 of 16 Photos: The Derby returns to Churchill Downs The Kentucky Derby is one of the most anticipated annual sporting events in America. Hide Caption 3 of 16 Photos: The Derby returns to Churchill Downs Justify, trained by five-time Kentucky Derby winner Bob Baffert, won last year's rain-soaked event on his way to winning the prestigious Triple Crown, which also includes the Preakness Stakes and the Belmont Stakes. Hide Caption 4 of 16 Photos: The Derby returns to Churchill Downs The horse didn't run as a two-year-old, meaning it bucked a 136-year trend with a win in last year's race. Hide Caption 5 of 16 Photos: The Derby returns to Churchill Downs The event is also dubbed the "Run for the Roses" because of the garland of 554 roses draped over the winner. Hide Caption 6 of 16 Photos: The Derby returns to Churchill Downs The horses are randomly assigned a post position before the race. There are multiple theories to which position is best. Hide Caption 7 of 16 Photos: The Derby returns to Churchill Downs The event is a chance to dress up, with all manner of hats and elegant dresses on show. Hide Caption 8 of 16 Photos: The Derby returns to Churchill Downs The men also jump at the chance to put on their glad rags. Hide Caption 9 of 16 Photos: The Derby returns to Churchill Downs Famous faces regularly flock to Churchill Downs for the Derby. Here, NFL stars Tom Brady and Rob Gronkowski soak up the atmosphere in 2015. A horse named after New England Patriot's tight end Gronkowski was due to run in this year's race, but had to pull out with a fever Hide Caption 10 of 16 Photos: The Derby returns to Churchill Downs American actor Jeff Bridges (left) was in attendance in 2017. Hide Caption 11 of 16 Photos: The Derby returns to Churchill Downs The hats are spectacular and rival the best Royal Ascot has to offer. Hide Caption 12 of 16 Photos: The Derby returns to Churchill Downs In 2015, jockey Victor Espinoza rode American Pharoah to victory -- his first win on the way to completing the Triple Crown. Hide Caption 13 of 16 Photos: The Derby returns to Churchill Downs It also meant Espinoza secured back-to-back victories after winning the 140th edition on California Chrome. Hide Caption 14 of 16 Photos: The Derby returns to Churchill Downs Punters prepare to place their bets at the wagering windows in 2014. Hide Caption 15 of 16 Photos: The Derby returns to Churchill Downs Trainer Bob Baffert saddled Justify to his fifth Kentucky Derby triumph in 2018. One more victory for Baffert would equal the record of Ben A Jones, set between 1938 and 1952. Hide Caption 16 of 16

'Pretty wild'

Baffert won his first Kentucky Derby in 1997 with Silver Charm and followed up with Real Quiet the following year, War Emblem in 2002, American Pharaoh in 2015 and Justify last year.

"It's the greatest race in America and to be that lucky, with 150,000 people at Churchill Downs with the Twin Spires, it's magical," he added.

"The thing about the Kentucky Derby, what makes it so great is you get this bond with the clients and the owners. You make great friendships from it and I think that's what horse racing does, you meet really interesting people especially at this level. I've met presidents -- I'm still waiting to meet the Queen.

"Now I like to see the clients, I like to see how giddy they get, they're so excited, it's funny, a lot of them forget their wives, their husbands, I stay back and make sure everybody gets in because it's pretty wild."

'In heaven'

The key to the Derby is having a horse with speed, according to Baffert.

"I'm looking for a horse that looks like he has speed that can go a mile," he said. "A horse that looks like he can go a mile-and-a-quarter, mile-and-a-half, they usually don't have the speed, there's 20 horses and they're going to get in trouble.

"Turning for home I want them up close, that's how you win the Kentucky Derby.

"That first 100 yards is just a lot of anxiety, they have to break away from the gate. I remember last year [Irish trainer] Aidan O'Brien asked me if I had any advice. I said, 'It's muddy, sloppy, 20 horses and those jockeys on a big day like this, they're savages.

"You've got to get away from the gate, if you don't and they come in front of you it's going to be brutal. If that happens get to your car and beat the traffic out. That's why the first 100 yards is just so critical."

Another win for Baffert would put him alongside Ben A. Jones -- from 1938-1952 -- as the only man to have trained six Derby winners, but he says it never gets old.

"It's a magical experience, if you're lucky enough to win you're like, 'Wow I'm the luckiest guy in the world.'

"If there's a heaven it's in that winner's circle."