Sloane Stephens shocks Petra Kvitova in blockbuster Wimbledon opener

WATCH: Sloane Stephens closes out Petra Kvitova on Centre Court

Sloane Stephens scored the first big upset of the women’s draw on Day 1, when she took out two-time Wimbledon winner Petra Kvitova, 6-3, 6-4.

When the tournament was last held in 2019, both Stephens and Kvitova were Top 10 players. Now unseeded, the American shook off a string of inconsistent results to win the battle of former major champions and knock out the No. 10 seed in just over an hour on Centre Court.

"Obviously playing against Petra, you have to bring your A game," Stephens said after the match. "I thought I played really well today. I'm just trying to keep the momentum going, trying to find that, like, good, consistent level again."

Though she trailed Stephens 1-2 in their head-to-head, Kvitova won their most recent encounter at the Dongfeng Motor Wuhan Open in 2019, and was coming off a solid run to the semifinals in Bad Homburg—where she played a classic match with fellow lefty Angelique Kerber.

Stephens has largely been a shadow of the player who peaked at No. 3 in the WTA rankings in 2018, but showed marked improvements throughout the clay-court season to reverse a 1-8 record that followed her from last fall’s Roland Garros through the Miami Open in March.

"There's definitely panic when you're on a losing streak," Stephens admitted. "I will say that. It's definitely, like, I have to change this, my racquet is not right, I need different shoes, I need a new coach. There is all of those things that creep obviously into your mind.

"But I think for tennis, it's so one week you could be pretty average and basic, and the next week you could be like quartering, semi-ing a Grand Slam and your whole world changes. I think kind of just having that perspective of, like, at any moment it could change and go the other way and life could be totally different. It's happened to me more than a few times in my tennis career, so you just have to be prepared."

A quarterfinalist at SW19 in 2013, Stephens made the most of her popcorn first-round clash, rallying from an early break to race ahead 5-2 and serve out the opening set to 15.

Kvitova looked to turn the tables in the second set when she earned a 0-40 lead on Stephens' serve, but the American saved four break points to regain the momentum—and broke serve herself in the very next game.

"I haven't played on grass in two years," Stephens said. "This is my first match back. I think for me it was more of just executing my game. I knew I needed to serve well and return well. Obviously a lefty on grass is like your worst nightmare, so I was super prepared to be diving for balls on the return, but I knew that I had to fight for every ball and make sure that I got my racquet on a lot of those balls. I did that super well today.

"Instead of being super passive, I was super aggressive on the returns. I was trying to make her play and be on her back foot. Obviously she likes to play super aggressive and inside the court. I knew I needed to play first-ball tennis, and I did that pretty well today, which is good."

With a match point on serve, Stephens knocked away an off-kilter forehand smack on the line to secure her biggest-ever win at the All England Club.

Up next for the unseeded American is either countrywoman Kristie Ahn or hometown favorite Heather Watson.

Sabalenka staves off Niculescu

No. 2 seed Aryna Sabalenka kicked off Day 1 action on No. 1 Court as rain kept the grounds quiet throughout the morning, surging past Romanian qualifier Monica Niculescu under the roof, 6-1, 6-4.

“In the beginning I was really nervous to open the Wimbledon and also be first playing on first court,” a breathless Sabalenka said in her post-match press conference. “I haven't played on the stadiums at Wimbledon.

“The atmosphere there was unbelievable. I enjoyed it, and the people were supporting really well.”

With her relentless slice and arrhythmic tennis, the former world No. 28 looked like a potentially tough out for the big-hitting Belarusian, but Sabalenka played phenomenal tennis for a set and a half and held firm to dispatch Niculescu in 76 minutes—striking a total of 48 winners.

The most important thing is to stay low and be there, like, 100%. On the grass you have control everything because you never know what can happen and it's really fast and really tricky to play. Aryna Sabalenka

“I never played on the new grass, like where nobody had ever played on it before," said Sabalenka. "I didn't really know what to expect, just that it's going to be really slow and I’d have to work on my approach game a little bit more on the warm-up.

“I also didn't want to lose this match because, like, it's opening match! There was a lot of people out there. I just wanted to enjoy my game. I didn't know what's going to happen on that court. I'm really happy from the first, I would say, points I felt really, really good on the grass, like on the new grass, and so with every point, I would say my nerves were going away. After a few games I was just really enjoying the court.”

In hot pursuit of a maiden major quarterfinal and two weeks removed from an early Roland Garros exit at the hands of Anastasia Pavlyuchenkova, Sabalenka will next face British wildcard Katie Boulter, who rallied from a set down to defeat American qualifier Danielle Lao, 6-7 (6), 6-3, 6-4.

“It's good to have another Slam coming, like, really quick. In the first two [grass] tournaments I was kind of trying to find my game, trying to understand what's going on the grass. I'm still trying to find my game on the grass, but it’s a little bit better compared to the last two weeks.

“Hopefully with every match I will play better and better, but for now I feel well and ready to go.”

Swiatek Solves Hsieh in tricky SW19 return

French Open champion Iga Swiatek made a triumphant return to the All England Club on Monday and held off one of the trickier first-round opponents in Hsieh Su-Wei, 6-4, 6-4.

Swiatek goes way back with Hsieh, who was on hand for a clinic the Pole participated in as a youngster, and hit through all the Chinese Taipei veteran’s craft to score her first main-draw win at Wimbledon.

A junior champion at SW19, the No. 7 seed won just one match on grass coming into the fortnight, and is surely still reeling from her Roland Garros title defense ending in disappointment with a quarterfinal defeat to Maria Sakkari.

Hsieh has had an even tougher go since reaching her first Grand Slam singles quarterfinal at the Australian Open, winning just one match since, but has become one of Wimbledon’s most dangerous floaters of late, stunning Simona Halep in 2018 and pushing Karolina Pliskova to three sets in 2019.

Swiatek ultimately countered Hsieh’s variety with an aggressive game plan—and some trick shots of her own—making 20 winners to 18 unforced errors and breaking serve three times to earn a spot in the second round, where 2010 finalist Vera Zvonareva or Marie Bouzkova await.