Canadian teen Summer McIntosh put the world on notice during the 400-meter freestyle heat in the swimming competition at the Tokyo Olympics on Sunday.

The 14-year-old finished in third place behind American superstar Katie Ledecky and set a national record with a 4:02:72 in the event.

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McIntosh is one of the youngest Olympians in the Games.

In May, she swam a 4:05:13 in the 400-meter freestyle which was the quickest time ever swam by a 14-year-old competitor. She won gold in the 200-meter and 800-meter freestyle in Canadian trials.

McIntosh also had a great performance in the Canadian Swimming Championships in 2019. She won silver in the 400-meter freestyle and bronze in the 400-meter individual medley and 800-meter freestyle.

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"I'm still processing everything. It doesn't feel real yet," she told CBC in the days leading up to the start of the Olympics. "But it's been great to see my hard work come to life and see that hard work always pays off."

United States' Katy Ledecky competes in a 400-meter freestyle heat at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo. (AP Photo/David J. Phillip)

Her mother, Jill McIntosh, competed for Canada in swimming at the 1984 Olympics.

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The teen will race in the 400-meter freestyle medal competition on Monday. Ledecky is the favorite to win the event as she took home first place in the heat.