NEW YORK, NY, USA -- Former Top 10 player Kristina Mladenovic of France notched a big win in the first round of the US Open on Monday, upsetting 2016 champion and No.14 seed Angelique Kerber of Germany, 7-5, 0-6, 6-4.

"Of course it’s a big thing for me to beat Angelique, for whom I have such big respect," Mladenovic said, after the match. "She’s such a great champion, with lots of experience in the Grand Slams. It’s never easy to beat such a player."

Mladenovic, who reached the 2015 US Open quarterfinals for one of her two career-best Grand Slam results, had lost four of her five previous meetings with former World No.1 Kerber. Mladenovic, however, turned the tables on this occasion to claim victory after two hours and 23 minutes of action.

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"It feels like a very big match that could be very deep in the tournament, but it’s just the first round," said Mladenovic. "I really want to enjoy [this] win, and then just focus on moving on and continuing in this tournament."

World No.54 Mladenovic had 45 winners to Kerber's 36, and won 23 of the 30 points when she ventured to net -- a super 77 percent success rate in the forecourt. Mladenovic saved 10 of 12 break points in the first and third sets combined, eking those sets out to negate the loss of the second set at love while she struggled with her game.

"I really wanted to go out there and give it my best, and make it as hard as possible for her," Mladenovic stated. "I really had the plan in my mind, and I really tried to stick with it, no matter the score, the length of the match from first to last point."

Following an early exchange of breaks, the players were evenly matched for much of the opening set, with Mladenovic’s fabulous forehands being countered by some stirring down-the-line winners from Kerber, reminiscent of her form in 2016 when she finished the year as World No.1.

It was Mladenovic, however, who ended up on top at a critical moment at 5-5, erasing two game points held by Kerber, then earning a second break point of that game by cracking a forehand winner. Kerber double faulted on the next point, ceding the game to the Frenchwoman.

A grueling game followed, as Kerber reached 0-30 with consecutive backhand winners before Mladenovic stormed back, reaching her first set point with a winning dropshot out of the air. The two jockeyed back and forth in that game, with Kerber holding two break points, before Mladenovic finally took the one-set lead, converting her fourth set point with another forehand winner.

Things turned dramatically in the second set, though. As she had in the first set, Mladenovic lost serve early, handing a 2-0 lead to Kerber with a double fault. This time around, however, Kerber consolidated her lead to take an imposing 3-0 advantage. After that game, Mladenovic had a medical time-out and had her back worked on.

After that, Kerber continued to roll through the second set, breaking at love for 4-0 and coming back from a 0-40 deficit to continue her run of games. Serving to stay in the set, Mladenovic erased Kerber’s first set point with a forehand winner, but a miscue off of that side on Kerber’s second chance allowed the German to tie up the match at a set apiece.

Mladenovic, though, came back roaring in the decider, crushing another forehand winner to break Kerber in the first game. The German, however, was hardly done yet, and after seeing four break points fall by the wayside due to gutsy, aggressive play from Mladenovic, Kerber finally got back level at 3-3 after a netted backhand from the Frenchwoman.

It would turn out to be Mladenovic’s day in the end, though, as a flurry of unforced errors from Kerber’s backhand gave the former World No.10 triple break point at 4-4. Kerber saved two with a forehand winner and ace respectively, but after another netted error on the third, Mladenovic had the 5-4 lead. The Frenchwoman coolly served out the match in the next game to earn the upset.

Mladenovic will play her fellow Frenchwoman, Fiona Ferro, in the second round. Ferro dispatched Australia’s Daria Gavrilova, 6-3, 6-4, earlier on Monday.