BUDAPEST, Hungary－The kids are alright.

Canadian teenager Summer McIntosh won the women's 200-meter butterfly for her first title at the FINA World Championships on Wednesday before 17-year-old Romanian David Popovici claimed his second.

They still have some way to go to match Katie Ledecky, who claimed her 18th gold at a worlds by helping the United States win the women's 4x200m freestyle relay. The 25-year-old Ledecky now has 21 medals, extending her record for the most among female swimmers at the championships.

Popovici won the men's 100m freestyle to add to the 200m free he won on Monday. He is just the second man to achieve the double at a worlds, after American swimmer Jim Montgomery in 1973, and he's the first Romanian swimmer to win two golds at a worlds.

"The airport is going to be chaotic but I am ready for it," Popovici said of his return to Bucharest.

"For Romania it means a lot and I love the feelings, even though I cannot explain it really well, I am very happy."

The 15-year-old McIntosh clocked 2 min 5.20 sec in the 200m butterfly to beat three Olympic medalists to the title.

"It's one of my biggest dreams in the swimming world to become world champion, and especially to do it in 200 fly is something I have always wanted to do because this is one of my favorite events," said McIntosh, who finished 0.88 seconds ahead of American Hali Flickinger.

China's Zhang Yufei was third and American Regan Smith was 1.59 seconds behind in fourth.

Popovici had to fight hard to edge France's Maxime Grousset by 0.06 seconds in the final with a time of 47.58.

Canada's Joshua Liendo Edwards, who was leading at the halfway stage, took the bronze.

Two-time defending champion Caeleb Dressel didn't race after withdrawing from the rest of the competition with an unspecified medical condition earlier on Wednesday.

The Americans had to wait until the women's 4x200m freestyle relay for their 11th gold of the championships as Claire Weinstein, Leah Smith, Ledecky and Bella Sims triumphed. Australia was second and Canada third.

"I am so proud," Ledecky said. "I think I realized when we were on the medal podium it had been a while since we had all been up there singing the national anthem together; trying to hit those high-pitched notes together. So that was a lot of fun."

Only the US (11 gold, six silver, nine bronze) and Australia (two gold, five silver, one bronze) had won at least one medal on each of the five nights of the swimming competition by Wednesday.

Kylie Masse claimed Canada's second gold of the night by winning the women's 50m backstroke ahead of American Katharine Berkoff and Analia Pigree of France.

Masse became the first swimmer from Canada, male or female, to win three golds at a worlds.

Leon Marchand won the men's 200m individual medley in 1 min 55.22 sec. The 20-year-old Marchand finished ahead of American Carson Foster and Japan's Daiya Seto.

It was Marchand's second gold at the Budapest worlds after the men's 400m medley on Saturday, when he almost broke Michael Phelps' world record, and his third medal after silver in the 200m butterfly on Tuesday.

"I was a little tired this morning," Marchand said.