LOUISVILLE, Ky. — Michael Matz is back at the Kentucky Derby with a strong contender for the first time since he won in 2006 with Barbaro, whose bronze likeness now greets all visitors to Churchill Downs.

Bob Baffert is a regular at the Derby, a three-time winner who’s been looking for No. 4 since 2002. Only this year, he returns a changed man. A heart attack has a way of doing that.

Either trainer could have the favorite for Saturday’s big race.

Matz trains Union Rags, who has never finished worse than third, while Baffert’s top horse among his two runners is Bodemeister, named after his 7-year-old son Bode.

Wrenching as it may be to recall Barbaro’s tragic end — he broke down in the Preakness and, despite a valiant fight, was euthanized nine months later — Matz doesn’t try to temper his delight to be back in the Run for the Roses.

“It’s a great feeling to be here after six years, especially with a horse that has a good chance,” Matz said. “This doesn’t happen too many times and I was lucky enough once. It’s hard to believe you can get lucky twice.”

Baffert knows you can.

His lifestyle of eating fried food and lots of meat, combined with already high cholesterol, caught up with him last month in Dubai, where he had gone to watch his horse, Game On Dude, run in the $10 million Dubai World Cup. He fell ill and was rushed to a hospital, where surgeons inserted three stents in two arteries.

“It was a pretty big scare for him,” said Bernie Schiappa, who co-owns Game On Dude. “He thought he was going to check out.”

“I wouldn’t listen,” Baffert said, understating that he’s “a little hard-headed.”

When his family isn’t around, Baffert has Schiappa to keep him on the straight and narrow. In Louisville, the duo has been hitting the hotel gym at 5:30 a.m. to exercise. Baffert does 30 minutes on the elliptical trainer followed by light weights.

“I’m training him, he’s training the horses,” Schiappa said.

Bodemeister’s owner, Ahmed Zayat, greeted Baffert with a big hug outside his barn Monday. The biggest change Zayat sees in Baffert is a new contentment.

“He doesn’t have to get everything done perfect,” Zayat said. “His demeanor is telling me that ‘I’m happy to have a second chance and now I’m going to try to enjoy it and try not to stress myself.’ “

That includes watching his horses during races. Instead of getting fired up, waving his arms and shouting, Baffert sticks to a more subdued, “Come on, boy.”

Mostly, though, Baffert’s new mantra is not to worry about things he can’t control, not an easy task for a perfectionist.

“I used to get upset over little things that I shouldn’t have even worried about,” he said. “This sport can really get you down. I’m actually enjoying my sport a little bit better.”

Bodemeister turned in the most dominating performance of any Derby prospect with a 9 1/2-length victory in the Arkansas Derby. He’s never been worse than second in his four career starts, all this year. He didn’t race as a 2-year-old and no colt since Apollo in 1882 has won the Kentucky Derby without running at 2.

Baffert said young Bode is more nervous about his namesake’s performance in the 1 1/4 mile race than his father.

“When I told him Bodemeister was going to the Kentucky Derby, his first question was, ‘Well, what if he loses?’ ” Baffert said. “I said, ‘Well, we can’t worry about that.’ It’s a little extra pressure for me to make sure that he runs well.”

Matz, meantime, has been quietly going about his business since hitting the big-time with Barbaro. While his champion, undefeated colt was trying to battle back, Matz won the Breeders’ Cup Ladies’ Classic that fall, making for a bittersweet year.

Union Rags, with four wins in five career races, is residing in the same barn that housed Barbaro at Churchill Downs; same exercise rider, too.

“We have some very nice memories from here,” said Peter Brette, who also works as Matz’s assistant trainer. “It’s really nice to be back with a horse that’s got a really good chance.”

Barbaro ran three times before the Derby, while Union Rags has had an even lighter schedule — just two starts, including a win in the Fountain of Youth Stakes after a strong 2-year-old campaign.

“I hope I learned something in six years,” said Matz, a former Olympic equestrian. “It’s just like anything else, probably the same thing you learned riding — experience.”