NEW YORK, USA - Iga Swiatek is only three-years younger than World No.1 Naomi Osaka, but the 18-year-old rising star from Poland admits to being starstruck when the two linked up for a practice session ahead of the US Open. 

"She is already a superstar and she's done an amazing job, especially at her age," Swiatek told WTA Insider after posting a 6-0, 6-1 win over Ivana Jorovic in her US Open main draw debut. 

"I'm still new here, so I'm not used to talking to celebrities. I know she's a human being and she's great. I've seen her other side, really down to earth. But still it's a little weird for me and I have to adjust."

The seeds for the Swiatek-Osaka practice session were sown earlier this month at the Rogers Cup in Toronto. Swiatek, who is enjoying her breakout season after making her Top 100 debut in April after making her first WTA final in Lugano, and then advancing to the Round of 16 at Roland Garros two months later. 

This summer, Swiatek tallied a strong comeback win over Caroline Wozniacki at Rogers Cup to set up her first meeting against Osaka in the Round of 16. Swiatek stepped up and put in her best performance of the season against top opposition, pushing Osaka hard in a 7-6(4), 6-4 loss. 

"We are both shy," Swiatek told WTA Insider. "I was amazed because I totally didn't know she was going to say nice things about me and she even tweeted my shot."

"I'm happy for her that she's having fun playing tennis right now and I hope she's going to play her best tennis at the US Open.

"She's 21 and she won two Grand Slams and there's a lot of pressure on her. If she'll play great then it's a perfect example for younger players that you can handle it. She has that."

Swiatek certainly left an impression on Osaka, who praised the youngster's heavy forehand and superior movement. 

"It's just so different, the way that she strikes the ball," Osaka said in Toronto. "I can't even compare it."

"But for me, the most impressive thing that I saw tonight was her movement. Like, she's a crazy good mover, just sliding. So hopefully I can learn that from her."

After setting up a future practice session on Twitter, Swiatek says it was Osaka who reached out in New York. 

"I met her dad at the restaurant and my coach and him exchanged numbers, and then Naomi texted me," Swiatek said. "I wasn't surprised, because she promised, but I was really happy and I still am. 

"She's a great person. I didn't know the World No.1 could be that down to earth. It was great that she gave me that opportunity and I hope we're gonna play more practices like that."

"When I play with her, I feel like my brain and my body is on another level and everything is working really well. I'm super focused."

The practice clearly paid off. Swiatek was sharp in her opening match against Jorovic, firing 24 winners to just 7 unforced errors in an efficient 51 minutes. Now into the Top 50 at No.49, Swiatek credits her summer hardcourt form to a change in attitude.

"Grass season wasn't really nice for me," Swiatek said. "I wasn't really fighting on court. When I got to Washington we tried to change my attitude. My psychologist wanted me to be more confident on the court, so we've done a lot of work. I guess that's why I'm playing good right now."

"I think it just clicked. Earlier I had boundaries, mental boundaries, that I couldn't break. I think I cracked it, I broke it. Now I'm on a higher level with my game. 

"When the ball was really fast I would back off and play higher, and that's an opportunity for the other player. It was in my head, my mind. I think that changed. We were also working really hard on my forehand, which wasn't the best in the grass season. 

"Everything, technical stuff, mental stuff, it all sums up to a great result."

Swiatek will play 12th seed Anastasija Sevastova in the second round, another opportunity to test her game against a crafty and solid player who is also the only woman to make the quarterfinals or better at the US Open the last three years. For now, Swiatek and her team are more concerned about learning than achieving, both on and off the court. As she competes at her first US Open, the high-schooler is balancing her playing schedule with studying for an upcoming trigonometry test. 

"We're not talking about goals because I just wanted to get experience," Swiatek said. "My only goal is to get into the Tokyo Olympics, but I have time. 

"We don't have any goals because you never know what's going to happen. I didn't know I was going to be in main draw at the US Open, I thought I was going to play qualies."

Playing her first full season on the WTA Tour, Swiatek says every opportunity she's had to hit or play against the best has led to accelerated improvement. 

"I was practicing with Caroline Wozniacki at the Australian Open and it struck me how fast she was hitting the ball," Swiatek said. "I had a problem playing in the rhythm. It was the highest level of tennis and the highest level of focus. 

"Now, it's not that fast for me. That's a test I passed."