GWANGJU: Caeleb Dressel is already earning comparisons to the great Michael Phelps and the best is yet to come, the 22-year-old from Florida said after winning three more events at the world championships on Saturday.

Dressel took his tally at the meet to six gold medals and has a chance to make it seven on Sunday, which would match his haul from the 2017 world Championships.

He got out to an early lead in the 50 metres freestyle, en route to an American and world championships record 21.04 seconds.

He was back in the pool some 30 minutes later for the 100m butterfly, where he exploded off the blocks "like a kangaroo" in the words of former Olympic champion Rowdy Gaines.

The unparalleled dive enabled Dressel to establish an early lead, and he prevailed in 49.66 seconds, the second fastest time ever, behind only his own world record of 49.50 set the previous night.

"Every time I do a race I always look for the bad, that's just how I work," said Dressel.

"My start (in the 50 free) was so bad, I wish I could have that one back. There's plenty to improve on.

"I think I had full potential to go under 21 (seconds). It was my best time, so I can't complain but I know I can be faster."

Dressel was happier with his start in the 100 fly, though not his finish.

"My wall at the second end was very, very sloppy. There's plenty of room for me to improve," he said.

Dressel completed his night by swimming the first leg on a United States team that set a world record of three minutes and 19.40 seconds in the mixed 4x100m freestyle relay.

He acknowledged it was a challenge juggling so many events.

"It was not easy in '17 and it was not easy this year," he said.

"I don't want it to be easy, I really don't. This is just about getting better every day ... It doesn't come together by accident. I knew what was ahead of me the moment I finished Pan Pacs last year and knew what I was qualified for.

"It took a lot of focus not only today but leading up to the meet. I'm glad it's over, I certainly don't want to swim any more events tonight but tomorrow I will be ready to swim one more and one more fast."

If he also wins that event, the medley relay, it will make it 14 world titles from two world championships.

Phelps won 26 golds from his six appearances at the worlds.