French Open 2021: No. 6 Bianca Andreescu upset by Tamara Zidansek in first round

The 2021 French Open is already off to a rousing start, with No. 11 Petra Kvitová coming back from a set one loss to beat Germany's Greet Minnen, and Naomi Osaka defeating Romania's Patricia Maria Țig (and then skipping her contractually mandated media obligations and drawing a $15,000 fine) on the first day alone. The following day, Roger Federer made his return to Roland Garros with a straight sets victory.

But just like every tournament, we've also seen that a high ranking doesn't mean anything once the players are on the clay. And early Monday on day 2 of action, upsets were in store.

Follow all the early-round upsets and surprise victories below.

Bianca Andreescu upset in three-hour thriller

Bianca Andreescu is out of the French Open after a three-hour, 20-minute battle with Tamara Zidansek in the first round on Monday. Andreescu fell, 6-7 (1), 7-6(2), 9-7.

It's Zidansek's first win over a top-10 ranked opponent and her first win in the main draw at Roland Garros. The 23-year-old is ranked No. 85 in the world.

She handed Andreescu her first tour loss on clay. Andreescu has played in three tour-level matches on the surface as injuries forced an odd playing schedule over the years.

Dominic Thiem falls in stunning upset

Until Sunday, Austria's Dominic Thiem had never lost in the first round of the French Open. In the last six years, he's made two semifinal appearances and played in the finals twice. But Sunday, 68th-ranked Pablo Andujar of Spain earned his first-ever victory over a Top 5 opponent when beat Thiem, the World No. 4, 4-6, 5-7, 6-3, 6-4, 6-4 over four hours and 28 minutes. Down 2-0, he won the last three sets for a stunning comeback win.

Through the first two sets, it looked like this match would be another regular Thiem early-round victory. But Andujar started turning things around late in the second set, clawing his way back from 5-4 to a narrow 7-5 loss. He took control in the third set, winning three straight games to close it out, and prevailed in the fourth set despite a surge from Thiem that included a nifty behind-the-back shot. After being down 1-2 in the fifth set, Andujar won 10 of the next 11 points while Thiem continued to look lost and unconfident.

Andujar is 35, and had not only never beat a Top 5-ranked competitor, but had never won a match after being down two sets to none. He ended both of those career droughts on Sunday. He was overwhelmed after his victory, but said he'd never stopped believing he could do it.

Angelique Kerber upset in Round 1 yet again

Angelique Kerber's 2021 French Open has ended not long after it began. The 33-year-old, who was ranked 27th coming into the tournament, lost 6-2, 6-4 in the first round on Sunday to qualifier Anhelina Kalinina, who was playing her first-ever match at Roland Garros.

Kalinina, hailing from Ukraine, got a strong start in the match and never let up. She was efficient on first serve points, winning nearly 60% of them, while Kerber was at 41%. Kalinina also broke Kerber's serve six times on 10 tries, while Kerber could only break Kalinina's serve three times in eight chances. Kalinina was better on big points, while Kerber didn't get her feet under her until it was too late.

“She started well and had nothing to lose, while it took me too long to get into the contest,” Kerber said after the match. "I will try to learn from the match now because I played good the last few weeks and I had good matches."

The French Open is the only Grand Slam that Kerber has failed to win, and she's struggled there in recent years. This is the third straight time Kerber has lost in the first round, and the fifth time in six years. She's made it to the quarterfinals twice in her career, in 2012 and 2018, but playing on clay has never been her strong suit, especially at Roland Garros. She told the media on Sunday that she's already looking forward to grass season.

“I did the best preparation I could do in the last few weeks on clay, but yeah, it’s fine, and now I’m looking forward to Wimbledon for the grass court season, and it sounds much better for me, so I’m happy that the next Grand Slam is on grass," Kerber said.

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