Caeleb Dressel has a saying: It’s a fine line between goal-setting and laughter. With that in mind, the Florida senior set an ambition so outlandish that it would have made plenty of people chuckle.

Dressel wanted to lower his time in the 50-yard freestyle to 17.6 seconds at the NCAA men’s swimming and diving championships. That represented a drop of more than half a second from his U.S. and NCAA record of 18.20, and it would make him the first person ever to swim the distance in less than 18 seconds. Thursday night, Dressel hit his mark at the Jean K. Freeman Aquatic Center, and it brought him his fourth NCAA championship in the 50 free.

The 21-year old stunned the crowd with a time of 17.63, winning the race by 1.01 seconds over Ryan Held of North Carolina State.

It was the latest milestone by a swimmer who won seven gold medals at last summer’s world championships, equaling a record set by Olympic legend Michael Phelps and drawing inevitable comparisons.

Indiana took the lead in the team race on Day 2 of the championships, topping a tightly packed group of five teams with 169 points. But everyone was talking about Dressel, and it’s unlikely anyone will laugh at whatever he sets his aim on next.

“I don’t think you should sell yourself short,” said Dressel, who also helped Florida win the 200 free relay Thursday. “17.6 was what I thought I was capable of doing. Maybe I lied to myself, but it worked.

“I’m super happy with it. I think everyone in the world of swimming expected 17.9, but I don’t really care about other people’s expectations. I want to set my own.”

Dressel has been doing that since he was a teen. He broke the first of several national age-group records when he was 14, toppling some marks that had stood for 20 years.

He won two gold medals at the 2016 Rio Olympics as part of U.S. relay teams.

His real coming-out party happened last July at the world championships in Budapest, Hungary, where three of those gold medals came in one night. Dressel holds five American records in short-course yards, including the 50 free mark he crushed Thursday.

“Honestly, if someone believes he’s not the best male swimmer on the planet, I’d like to debate it with them,” Gophers coach Kelly Kremer said.

“I think he will do things in the short-course yards pool that will stand for a while. He’s the best swimmer I’ve seen.”

In three swims Thursday, Dressel peeled .57 of a second off his 50 free record. He seemed to do it easily, bursting off the blocks with his typical quick start and immediately pulling away from the rest of the field.

Dressel swam a time of 18.11 to top the morning preliminaries of the 50 free. In the finals of the 200 free relay, he broke the 18-second barrier with a leadoff leg of 17.81, giving the Gators a gigantic lead that withstood an outstanding team effort by North Carolina State.

All four Wolfpack swimmers finished in less than 19 seconds to earn a time of 1:14.50, an American record.

Before the 50 free, a placid-looking Dressel came out wearing mirrored goggles and a blue towel on top of his head. A standing-room crowd whistled and whooped throughout the race — called the “splash and dash” for its brevity — and raised the volume even more when they saw his time. Dressel got a hug from Held, then slapped the water in exhilaration.

“Jaw-dropping,” said Florida teammate Jan Switkowski, who also was part of the winning 200 free relay team. “Just seeing everyone in the stands, they just didn’t know what’s going on. It’s absolutely amazing.

“I’m fortunate I get to witness it.”

After the race, Dressel gave his trophy to a child volunteering at the meet, then turned his attention forward.

He will swim two other individual events, the 100 free and the 100 butterfly, and is the defending NCAA champion in both.

He didn’t say what times he might be pursuing. But after Thursday, nothing seems impossible.

“The 17.6 was just a number that popped into my head,” Dressel said. “You’ve got to maybe joke with yourself, maybe make up some times.

“Then, believe you can do it.”