Leon Marchand and Summer McIntosh are sure to star in the pool at Paris Olympics

FUKUOKA, Japan — Watch out for these two young swimmers when you take in next year’s Paris Olympics: 21-year-old Leon Marchand of France and 16-year-old Summer McIntosh of Canada.

Marchand won his third gold medal at the swimming world championships, taking the 200-meter individual medley on Thursday in 1 minute, 54.82 seconds.

Add this to his earlier gold in the 200 butterfly, and his world record in the 400 IM — the last individual record held by Michael Phelps. Marchand obliterated it by more than a second, finishing in 4:02.50.

“It was amazing, and I’m very proud of it,” said Marchand, who pushed British teammates Duncan Scott to silver (1:55.95) and Tom Dean to bronze (1:56.07).

“It was a very painful race, but exciting,” Marchand added. “Almost killed me, but it was good.”

Marchand trains at Arizona State University under Bob Bowman, who coached Phelps to 23 Olympic gold medals.

McIntosh won her first gold after coming up short in two earlier races where some billed her as a favorite. She was fourth in the 400 freestyle and took bronze in the 200 free.

McIntosh won the 200 butterfly in 2:04.06, repeating her title from last year’s worlds. She also set a world junior record.

Elizabeth Dekkers of Australia took silver in 2:05.46 and Regan Smith of the United States earned bronze in 2:06.58.

“Going into tonight I just wanted to see how hard I could push and how much I could hold on in the second half,” said McIntosh, who won by a full body length.

It’s unfair to say that McIntosh’s first two races were disappointing, but she did lose her world record in the 400 free to Ariarne Titmus of Australia.

Another one to watch is 18-year-old David Popovici of Romania. But he was disappointing at the worlds in southwestern Japan.

Popovici is the world-record holder in the 100 free with a time of 46.86, but in that race on Thursday he was sixth behind winner Kyle Chalmers of Australia (47.15), silver medalist Jack Alexy of the United States (47.31), and Maxime Grousset of France (47.42). Popovici finished in 47.83.

Popovici was fourth earlier in the meet in the 200 free.

He suggested he might have raced too much, and will need to train harder to stay on top. Getting there was the easy part.

“I feel good. I feel good that it’s over,” he said. “After I take some time off for myself and clear my head — reflect on this very busy and weird year — I’m going back to the pool. And fortunately for me, what hasn’t gone perfectly here is trainable. I’m going to be just fine.”

Popovici’s 200 was a red flag.

“As soon as I touched the wall in the 200, this thought flashed in my head, which was: I need to train better. I need to train more,” he said. “And more importantly, I need to be more consistent. That’s the glue that holds it together.”

The other end of the emotion spectrum was Chalmers, who won Olympic gold in the 100 free in Rio de Janeiro when he was 18. Now’s he’s finally added the world title, which completes the the gold set.

He referred to going through shoulder surgery, heart surgery and “some pretty bad mental health times” in his seven-year return to gold.

“In 2016 I was an 18-year-old and I probably didn’t know what I had achieved,” he said. “For me, I’ve had to work so hard for seven years and sacrifice so much. I wanted to make sure that the early-on wasn’t a fluke.

“There were times I thought I’d never get back to swimming fast,” he added.

Kaylee McKeown led from start to finish to pick up gold in the women’s 50-meter backstroke. The 22-year-old Australian got off to a fast start and held on to prevail in 27.08. Smith won another medal and took silver in 27.11, and Lauren Cox of Britain got bronze in 27.20.

Australia won the women’s 4×200 freestyle relay in a world-record time of 7:37.50. The United States took silver in 7:41.38, and China grabbed bronze in 7:44.40.

The top three finishers automatically qualified for the Paris Olympics.