Swimmer Summer McIntosh, the first Canadian to win three gold medals in a summer or winter Olympic Games, captured the women's 400-metre freestyle in world record time for her first individual world short course championship gold medal on Tuesday in Budapest, Hungary.

In her first major race since the Paris Games in July, McIntosh led from start to finish, touching the wall in three minutes 50.25 seconds. The previous world mark of 3:51.30 was set by Li Bingjie of China on Oct. 27, 2022.

McIntosh's performance also set an Americas record and world junior record for the 18-year-old. Her 3:52.80 previous best in the 400 free was also a Canadian mark.

"There's been so many other amazing swims tonight for Team Canada and this is just Day 1," McIntosh, who was awarded $25,000 US for her efforts, stated in a Swimming Canada news release. "The next couple days of racing should be awesome and we'll just try to keep the momentum going."

"This is definitely one of my favourite, if not my favourite, pool in the world because it holds so many memories and it's a really fast pool," McIntosh told Devin Heroux of CBC Sports this week at a training session ahead of the event.

A few hours later, McIntosh was named the recipient of the Northern Star Award as Canada's athlete of the year (formerly the Lou Marsh Trophy), with media members from across Canada voting Tuesday on the annual Toronto Star award.

CBC Sports analyst Brittany MacLean said the 400 freestyle has been "a bit of a mental hurdle" for McIntosh since she hadn't won the race previously on the international scene.

But McIntosh started strong Tuesday and held the pace with long strokes and moved well in and out of the walls through 16 lengths of the pool at Duna Arena.

Mary-Sophie Harvey of Trois-Rivières, Que., who sat fourth with fewer than 25 metres to the finish, took bronze on Tuesday in 3:54.88, her first international individual medal. Australia's Lani Pallister (3:53.73) collected silver after winning the race at 2022 short course worlds in Melbourne.

"It's always been a dream of mine. For years I was like, 'the relay swimmer.' and it feels really great to finally step on that podium individually," said Harvey, who trains at Montreal's CAMO Club. "To say that I've done it for the first time and I'm 25, I think it just shows that you can still dream later in life. And I think it's just the beginning of a good week."

Added MacLean: "She said this week [medalling] was her goal. She had an opportunity, she loves to race and she made the most of it. She stayed in the mix [for a medal] the whole time and made the move [over] the final 50 [metres]."

McIntosh to swim 3 other individual events in Budapest

In October, the 25-year-old Harvey clinched gold in the 400 free with a 3:56.78 personal best at a World Aquatics event in Incheon, South Korea.

McIntosh will also be competing in the 400 individual medley, 200 butterfly and 200 backstroke in Budapest, the first time she'll be competing internationally in a backstroke event. 

The short course championship is contested in a 25m pool instead of 50m.

WATCH | CBC Sports' Devin Heroux and Brittany MacLean recap Day 1 in Hungary:

Summer McIntosh shatters 400m freestyle record | Short course worlds day 1 recap

CBC Sports' Devin Heroux and Brittany MacLean discuss day 1 of short course worlds.

Two years ago in Budapest, a 15-year-old McIntosh became the youngest Canadian to win a world title, capturing her first two individual titles at long course world championships in the 200 butterfly and 400 IM in world junior record times.

Brent Arckey, her coach with Sarasota Sharks swim club in Florida, says this week's competition is another opportunity to evaluate McIntosh and build off of her Olympic performance.

"She can be as good as she wants here. You know she's going to ring it out. When she gets behind the blocks you know she's going to give you 110 per cent," Arckey said.  "She's proud to wear the flag and she's going to do everything she can to put on a show."

McIntosh is joined by 17 Canadians who make up a strong team with depth and talent including Kylie Masse, Sydney Pickrem and Penny Oleksiak. Fifteen out of the 18 swimmers on the roster competed on the Paris team that won eight medals.

The meet ends Sunday when McIntosh races the 200 backstroke.

WATCH | McIntosh 1-on-1 from poolside in Budapest:

Ahead of short course worlds, Summer McIntosh reflects on life post-Paris

After winning 3 gold medals at the Paris Olympics, the 18-year-old swimmer sat down with Devin Heroux in Budapest to talk about expectations moving forward.

Women threaten Canadian relay mark

Later Tuesday, Oleksiak anchored the Canadian women to bronze in the 100m free relay, stopping the clock in 3:28.44, or 38-100ths shy of the national record held by Rebecca Smith, Taylor Ruck and the now-retired pair of Maggie Mac Neil and Katerine Savard.

Harvey, McIntosh and Ingrid Wilm put Canada third when Oleksiak entered the pool Tuesday and slipped to fourth before the Toronto native put them back in medal position behind the Americans (3:25.01 world record) and Australia (3:28.25).

WATCH | Canadian women grab 4x100m freestyle relay bronze in Budapest:

Canada caps 1st day of short course worlds with women's 4x100m freestyle relay bronze

The quartet of Penny Oleksiak, Ingrid Wilm, Summer McIntosh and Mary-Sophie Harvey won bronze in the women's 4x100-metre freestyle relay, to cap a four-medal opening day for Canada at the World Aquatics short course championships in Budapest.

Harvey, who covered 1,300 metres over three races Tuesday, achieved a 52.40 PB in the opening leg of the relay.

"I didn't want to let anyone down," she said of her teammates, "and we wanted to get the job done tonight. It's a nice surprise because we weren't sure [Monday night] if we were going to swim [the event] but decided to enter."

McIntosh, Ruck, Mac Neil and Oleksiak placed fourth in the 100 free relay final at the Paris Olympics.

Also in Paris, where she didn't race individually, Oleksiak delivered a spectacular 52.93-second freestyle leg in the medley heats but wasn't selected to compete in the final.

"All the girls banded together, wanted [a medal] and we got it," Oleksiak, who turned in a 52.01-second split — her fastest since 2016 — said after Tuesday's race. "[Canada has] so many medals already and [other] opportunities coming, so I think it's going to be a good week."

Knox sets Canadian mark in 200m medley

On the men's side, Finlay Knox of Okotoks, Alta., picked up bronze in 1:50.90, holding off Carson Foster (1:51.32) of the United States.

The 23-year-old Knox also set a national mark, eclipsing his 1:51.04 from Dec. 13, 2022 in Melbourne.

Foster's teammate, Shaine Casas, topped the eight-man field in 1:49.51 for a championship record. Italy's Alberto Razzetti (1:50.88) grabbed silver.

"Post-Olympics, everyone's in different spots, and I know myself, I took a lot longer of a break than I usually do," said Knox, the reigning long-course champion in the event. "Going into this competition, I wasn't maybe as fit as I should be, but the overarching thing with all competitions is if you're there mentally.

"I made sure to go in there mentally as tough as I could be, and put down the best performance I could on the night. It was a little long on the touch, 2-100ths off silver, but to get back on the podium at the first major competition since the Olympics, I'm pretty happy."

WATCH | Knox holds off American Foster for 200m medley bronze:

Alberta's Finlay Knox breaks Canadian 200m IM record to claim bronze at short course worlds

Finlay Knox of Okotoks, Alta., swam to a Canadian record in the 200-metre individual medley, with a time of 1:50.90, to earn a bronze medal at the World Aquatics short course championships in Budapest.

Knox set a 1:56.07 Canadian record in the event on May 18 to qualify for a spot at the Paris Olympics.

At long course worlds in February, Knox lingered around third place through the butterfly, backstroke and breaststroke lengths, biding his time while Foster and Casas set the pace.

But the Canadian surged to the front of the pack with a blistering 27.79-second freestyle length to take the gold medal in a then-national record 1:56.64.

Other Canadian results Tuesday:

• Mary-Sophie Harvey, 4th, women's 200m medley final (2:04.30)
• Timothe Barbeau, 8th, men's 1,500m freestyle final (15:02.76)
• Ilya Kharun reached the men's 50 butterfly final with the third-fastest overall time in the semis. The double Olympic bronze medallist will try for the second individual short course world medal of his career on Wednesday at 12:42 p.m. ET.
• Blake Tierney covered the men's 100m backstroke in 50.03 seconds to secure the eighth and final qualifying spot for Wednesday's final, scheduled for 11:40 a.m. Hungarian Hubert Kos qualified first in 49.03.
• Ingrid Wilm (55.83) and Kylie Masse (56.06) advanced to Wednesday's final of the women's 100m backstroke (11:32 a.m.) placing third and fifth, respectively. Masse won the long-course world championship in the distance here in 2022.

WATCH | Day 1 coverage of event finals from short course worlds:

World Aquatics Swimming Championships (25m) 2024: Day 1 finals

Watch the evening session, on day one of the World Aquatics Swimming Championships (25m) from Budapest.