Bieber, 21, stood alongside the Canadian team and helped the games participants get pumped up during the first day of the nine-day event in Los Angeles, California.
"Turn on @espn now! Let's to Canada," Bieber Tweeted, sharing a video of himself chanting "Let's go Canada" with the athletes.
Xavier Collin / Image Press / Splash News Online
"#specialolympics," Menounos captioned the group shot. "Justin gave me a sneak peak of his new single-so cool!"
Apparently Bieber previewed and performed his upcoming track for the TV host.
"He even sang along which was even more cool," she wrote.
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The event, which allows thousands of intellectually disabled athletes to compete in 25 sports, was kicked off by a speech from First Lady Michelle Obama.
"To all of our athletes, I just want you to know that all those people won't just be cheering for you, they're going to be learning from you," said Obama. "They're going to be inspired by you. And they'll be reminded that at our core, we all want the same things – a sense of pride in who we are, and a belief that we can reach our dreams no matter what challenges we face.