Taylor Fritz, Frances Tiafoe, Madison Keys and Jessica Pegula have made fast starts at the Australian Open, with the quartet dropping just three sets between them in seven matches. Pegula and Keys booked their spots in the third round on Wednesday.

It follows their success at the United Cup earlier this month, when the ATP and WTA stars joined forces to guide Team United States to the title at the inaugural mixed-teams event.

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Throughout the 11-day tournament, the Americans shared jokes about being locked-in on court as they built a strong team dynamic in Sydney. Now in Melbourne, the quartet continues to support each other, with Fritz and Pegula drawing locks on the camera following wins at the major.

“[You] just have to stay locked," Tiafo said. "It's the whole thing with the United Cup guys. Just staying locked in. I made a joke about it with the guys at the United Cup asking them before the match, ‘Are you locked?’ It's definitely become a thing. It's so funny how true it is because staying between the lines, it's amazing how well you play. It's a funny thing with everybody.”

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Tiafoe is known on and off court for his energetic and relaxed personality. However, it was the 24-year-old who pushed the term "locked" at the United Cup, sparking laughter from his teammates.

“It's funny coming from me because everyone knows how I go about my business," Tiafoe said. "I'm very open and just joking around. When I'm saying it, it just sounds funny. So then it became a thing where if Frances can lock, everyone has got to lock. That's kind of how it all came around. ... We're all doing well, and it's becoming a good team camaraderie.”

Keys earned five wins at the United Cup at the start of the season and has backed that up in Melbourne, advancing to the third round.

"It is a Team USA thing," Keys said, when asked about the locks. "Unfortunately, Taylor's was so bad. So I guess for whatever reason today we decided that we would all lean in and try to explain what Taylor was trying to do for him.

"So, yeah, it's just us being dumb."

A semifinalist in Melbourne last year, Keys remains undefeated on the year and feels the mixed-teams event was the perfect way to begin her year.

“I think I speak for everyone, it was truly the best two weeks of my whole life. It was so much fun,” Keys said. “Obviously winning is the cherry on top and all of that. To have the seven other amazing people and then all of our teams together, it was just a really great group of people. I think it was the perfect way to start the year.

“We had so much fun. I'm really happy that we've continued to talk literally every single day. We still have meals together and all of that. So I think just carrying that over outside of the event has been really great for all of us.”

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