NEW YORK -- The two World No.1s on the Hologic WTA Tour and ATP Tour teamed up for some mixed doubles at the US Open on Saturday and the raucous crowd got more than they bargained for.

Iga Swiatek and Carlos Alcaraz took part in Arthur Ashe Kids' Day and impressed everyone with their soccer skills. The duo played a few points of football tennis and showed just how focused and competitive they can each get by winning a one-minute point and unleashing some classic celebrations.

Watch the point below:

For the first time since 2019, the reigning US Open champions have returned as the No.1 seeds. Reflecting on her title run last year, Swiatek said it was one of the most pivotal moments of her career.  

"I learned a lot during the US Open," Swiatek said at US Open Media Day on Friday. "This was probably the most important tournament in terms of me believing in myself and progressing on hard courts."

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Swiatek has already enjoyed three successful title defenses this season, having won back-to-back in Doha, Stuttgart, and Roland Garros. She's also posted career-best results at her last five tournament appearances. That run started with her first grass-court semifinal in Bad Homburg, her first Wimbledon quarterfinal, a first title on home soil in Warsaw, and back-to-back semifinals in Montreal and Cincinnati. Prior to this year, she had yet to progress past the Round of 16 at either event. 

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"I'm really happy with my performance in Montreal and Cincinnati," Swiatek said. "I get more positive vibes, for sure than before last year's tournament.

"But being the defending champion is not easy, so I'm kind of taking it easy, trying to do everything step by step."

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Swiatek has won three of the last six majors, but she played down any suggestion that another US Open would be easy pickings.

"I wouldn't say so because all of us can win these tournaments," Swiatek said. "You have to be ready anyway. Even if you won all these tournaments, it doesn't mean that you don't have to work tennis-wise the same way, be really intense, and mentally also be ready.

"For sure I take confidence from [my past victories]. I feel like at Grand Slams I'm kind of more efficient. These are the tournaments that I focus on."

Swiatek will open her tournament on Monday against Sweden's Rebecca Peterson.