Bob Baffert was back where he once ruled, standing behind the twin spires of Churchill Downs, boots in the dirt and his trademark white hair glistening beneath a Kentucky sun that seemed to welcome him home.

After a three-year suspension from the storied Kentucky Derby following a failed drug test, the Hall of Fame trainer returned this week with a familiar swagger and a chance to win his seventh Run for the Roses.

“It’s like I never left,” Mr. Baffert told reporters this week in Louisville. “It’s nice to be back at the old barn. This is like the Masters. It lasts all week, and everything has to be great.”

A six-time winner of the Derby, Mr. Baffert at one point had two horses entered in Saturday’s 151st edition of the Run for the Roses. His best chance in a 20-horse field filled with speed earlier appeared to be Rodriguez, sired by Authentic, which won the 2020 Kentucky Derby for Mr. Baffert. But Rodriguez, winner of the Wood Memorial, was scratched on Thursday because of a foot bruise.

That leaves Citizen Bull as Mr. Baffert’s lone entry. Citizen Bull was a three-time winner on the Derby trail before a fourth-place finish at the Santa Anita Derby. “You can draw a line through that last race,” Mr. Baffert said. “He’s better than that. He thinks he’s King Kong. You’re going to see the real Citizen Bull.”

Mr. Baffert, winner of 17 Triple Crown races, missed the last three Kentucky Derbys while serving a suspension for a failed drug test that disqualified the 2021 Kentucky Derby winner, Medina Spirit. He called the suspension “a very steep price,” but wants to put that chapter behind him. “In racing as a trainer, I never look back,” he said. “I turn the page. I accepted it and moved on.”

Citizen Bull, a 20-1 longshot earlier in the week, faces a fast and unpredictable field in this year’s Derby, where light rain is in the forecast. Journalism, trained by Michael McCarthy, is the favorite. Sired by Curlin, Journalism has won his last four races and drew post position 8 in what is expected to be a fast and contentious race.

Sandman, trained by Mark Casse, and Sovereignty, trained by Bill Mott, follow with the next lowest odds. Sandman, sired by Tapit, won the Arkansas Derby, while Sovereignty, sired by Into Mischief, is a late closer that finished second in the Florida Derby.

Being a favorite means little in the Derby. Justify in 2018 was the last race-time favorite to win the Derby. Mystic Dan, an 18-1 longshot, won the 2024 Kentucky Derby in a photo finish over Sierra Leone and Forever Young. Mage, the 2023 Kentucky Derby winner, was 15-1.

“These horses need to bring their Super A game, and they have to get a [good] trip,” Mr. Baffert said. “I’ve won it with the best horse, and I’ve lost it with the best horse. With 20 horses, you need a lot of luck. But they have to be ready.”

The race is loaded with speed horses. Potential early frontrunners could include American Promise, trained by D. Wayne Lukas, Neoequos (Saffie Joseph Jr.), Admire Daytona (Yukihiro Kato), and East Avenue (Brendan Walsh).

Todd Pletcher, trainer of Grande, another late scratch due to a bruised foot, expects a tactical trip around Churchill Downs. “It’s always a jockey’s race,” Mr. Pletcher said. “When there’s a fast pace, you have to be careful. Your natural instinct is to stay in contention, but if they’re going really fast, you have to stay in your comfort zone.”

The top closers in the race are Publisher (Steve Asmussen), Tiztastic (Asmussen),  Chunk of Gold (Ethan West), Coal Battle (Lonnie Briley), Sandman, and Sovereignty. A wild-card is Luxor Café, sired by 2015 Triple Crown winner American Pharaoh and trained by Noriyuki Hori. He won his last four starts, all in Japan.

With two entries, Mr. Asmussen hopes to claim his first Kentucky Derby win after failing to win the roses with 26 previous starters. “It’s more than significant and something I do more than just think about,” Mr. Asmussen said this week. “I don’t know if it’s healthy to want something that bad. Maybe that’s why it has eluded me.”

The Derby always promises drama. The crowded field, the weather conditions, and the huge crowds add the excitement and unpredictability of the mile and a quarter race toward glory and maybe redemption.