NEW YORK - As Billie Jean King's famous adage goes, "Champions adjust." That's precisely what No.8 Iga Swiatek and No.9 Barbora Krejcikova, the last two Roland Garros champions, are doing. And they've had to do it quickly.

This time last year, Swiatek had just finished high school and adjusting to full-time life on the tour as a promising teenage talent ranked No.53. Krejcikova was a Top 10 doubles player, who opted not to make the trip to New York, opting to stay in Europe instead to play a series of ITF 25Ks to boost her singles ranking to get closer to cracking the Top 100 for the first time. She was ranked No.116.

Twelve months on, they are both major champions, have won three career titles and are ranked in the Top 5 on the Porsche Race Leaderboard. Their dual ascensions to the top of the game have been swift and stunning, and both humble champions have confessed it's taken time for their mind to catch up to their accomplishments.

WTA Insider spoke to both champions as their US Open campaigns began.

Bookish Swiatek adapts to the times

As Swiatek packed up her bag after her 6-3, 6-4 win over Jamie Loeb in the first round, keen observers would have noticed an enormous tome sticking out of her racquet bag. The 20-year-old is on the verge of finishing Margaret Mitchell's 1,000 page classic, "Gone With the Wind."

"It will be pretty weird when I finish it because I've been reading it for three weeks now," Swiatek told WTA Insider. "I wanted to pick an American classic that was very long so I didn't have to switch books every couple of days."

The 2020 French Open champion has made the Round of 16 or better at her past four majors, and she's eyeing her first second-week appearance at the US Open. After taking a much-needed rest after a non-stop summer, Swiatek says her practice sessions have been going well. Before the tournament, she practiced with the top two seeds in No.1 Ashleigh Barty and No.2 Aryna Sabalenka. Swiatek said the sessions rekindled her underdog fire.

"Right now I can feel that with my ranking it's sometimes easier to practice with players who have a better ranking than me," Swiatek said. "I know in practice you shouldn't look at rankings and I know that's stupid, but everyone is doing it anyway. It's hard sometimes to separate it. 

"But I can see that with top players, it's back to normal, back to one year ago when I was still an underdog, back when it was easier. It was nice to have that feeling again. But it would be nicer to learn how to play as not an underdog. I'm giving myself time."

"I came to win, I came prepared, but in a match it's a different story. I know I can play good tennis but in a match I have to use different skills."

"Yesterday when I was practicing with Ash, they were making little bets on what I was reading."

- Iga Swiatek

On practicing with Barty, Swiatek marveled at the World No.1's focus and ability to reset between points. 

"It's really inspiring," Swiatek said. "Practicing with Ash is different because you can see her mentality and the way she treats things. When she makes a mistake, she's not frustrated. She doesn't seem to. Even when she is frustrated she uses it to play better and better. 

"So I'm trying to learn from her. I think I need a few more years to understand completely how to get there. But she's a great player to watch and take some lessons from her."

As for what book Swiatek will tackle next? That may remain a mystery for the foreseeable future. 

"I decided today that I'm pretty sure that I'm going to read that type of book on a Kindle because everyone is asking me what am I reading. Is it a book or is it a brick?" Swiatek said. "Yesterday when I was practicing with Ash, they were making little bets on what I was reading. It was pretty funny."

Krejcikova's surprising hot streak debuts in New York

Reigning French Open champion Krejcikova couldn't hide her disbelief. After defeating Christina McHale 6-3, 6-1 to advance to the third round in her US Open main-draw debut, the Czech was asked if she was surprised that she has played so well since her Paris triumph. With the win, Krejcikova has now won 27 of her past 30 matches since the start of Strasbourg. Her three losses have come to No.1 Barty twice (Wimbledon, Cincinnati) and Gold Medalist Belinda Bencic (Olympics). 

Krejcikova began to answer before sighing and putting her head in her hands.

"It's amazing," Krejcikova said. "I mean ... I cannot believe it. I cannot believe it's happening. 

"I was actually expecting that I was not going to do well after Paris. I was preparing myself mentally. It was a huge two weeks for me. I felt there were a lot of tough situations I had to go through. After that, I thought I just need to rest. I just felt so exhausted. I played many matches, obviously.

"I was preparing myself that maybe I'm not going to be doing that good. I wasn't really thinking about winning or losing or doing a streak, or winning this player or that player. Every time I step on court I just want to play my best tennis. I want to do the things I'm working on. I just want to play my game. If I do this and I lose, it's ok. It's part of the process."

"A year ago I wasn't dreaming of this. I didn't believe I could be on the stage or that I could ever play the main draw here."

- Barbora Krejcikova

Every week seems to bring unchartered territory for Krejcikova, who said she simply never thought she would ever get the chance to play in the singles main draw at the US Open. At this time last year, the doubles star had yet to crack the Top 100 in singles. Now, she's a reigning major champion, World No.9, and sits at No.2 on the Porsche Race Leaderboard. 

"It's not just another US Open," Krejickova said. "Now I'm playing singles and I'm in the third round. A year ago I wasn't dreaming of this. I didn't believe I could be on the stage or that I could ever play the main draw here." 

On Wednesday, Krejcikova's match was moved to Louis Armstrong Stadium to finish when the rain came and she marveled at her first foray on the show court as a singles player.

"I hope it's obvious from me and my attitude that when I step on court I really enjoy it and that I have a lot of fun out there. I just want to perform the best tennis and every time I step on court, improve as a player. 

"For me, being here, having this chance, it's unbelievable. It's actually unbelievable. I never expected that I could be this high and play on this stage."

On Friday, Krejcikova will play Russia's Kamilla Rakhimova, a 20-year-old lucky loser from Russia. Rakhimova has defeated Kristina Mladenovic and No.32 seed Ekaterina Alexandrova to become just the fourth lucky loser to make the third round in the Open Era at the US Open. A win would put Krejcikova into her third straight second week at a Slam.