Two-time champion Kim Clijsters made her first appearance in ten years at the BNP Paribas Open on Thursday, but the former World No.1 fell at the first hurdle.

Katerina Siniakova of the Czech Republic outlasted Clijsters of Belgium 6-1, 2-6, 6-2 in 1 hour and 36 minutes to pick up her first singles win since the first round of the US Open.

In the Czech’s first meeting with Clijsters, Siniakova fended off a valiant second-set comeback from the four-time major champion before regrouping in the third set and collecting her first singles win at Indian Wells since 2018.

"It was really special," Siniakova said on court after her win. "I was actually looking forward [to this], because I remember when I was young, and I was watching her play, and she always did amazing. So it’s unbelievable I could stay with her on the court."

By moving forward, Siniakova sets up a second-round meeting with another former World No.1 and multiple-Grand Slam champion, No.10 seed Angelique Kerber.

Clijsters won the BNP Paribas Open in 2003 and 2005, and last played the event in 2011 before her retirement in 2012. After an eight-year absence from the tour, Clijsters returned to action early last season, and she went 0-3 in 2020 after close losses to Garbine Muguruza, Johanna Konta and Ekaterina Alexandrova.

Clijsters made her 2021 season debut last week in Chicago, losing to Hsieh Su-wei in three sets. The Belgian has now played five matches since her return, and though she has been in contention in all of them, she is still looking for the first win of her comeback.

"Last week in Chicago, I started off well, but had a few games where I just really wasn’t into the match," Clijsters said. "Here too, just looking for my rhythm, my anticipation again, reading my opponents, getting used to playing on a bigger court again, a lot of different things. I fought my way into the match well in that second set, and I kind of put her under pressure a little bit better.

"I think overall, there’s definitely moments where I’m feeling really good out there, and there’s moments where I feel too inconsistent. That’s part of this process in general, it’s not going to be a smooth ride, and that’s what I’m going to try to improve every time I’m out there."

This time, it was World No.53 Siniakova who got the better of Clijsters, taking advantage of key points more than the 38-year-old former No.1 did. Each player held nine break points, but Siniakova converted six of hers, while Clijsters could only convert three.

Siniakova never faced a break point as she swept through the first set in 27 minutes. But Clijsters made her move at the start of the second set, converting her fifth break point of a nine-minute opening game. That break propelled Clijsters to a 4-0 lead in the second set, and she held on from there to level the match.

But strong volleying by Olympic doubles gold medalist Siniakova helped her attain an early break for 3-1 in the third set. Speedy Siniakova drew errors from Clijsters to fend off break points in each of her next two service games en route to 5-2. The Czech then closed out the win with another break after Clijsters sent a volley wide on match point.

Veterans Garcia, Sevastova book second-round spots with three-set comebacks

Earlier on Thursday, former Top 10 player Caroline Garcia will be American teenager Coco Gauff's first opponent in her debut at the BNP Paribas Open, after the Frenchwoman sealed a 5-7, 6-4, 6-0 victory over Belgian qualifier Kirsten Flipkens. 

Checking in at World No. 59 in the rankings in the rankings this week, the former World No. 4 won nine straight games to seal a 2 hour, 9-minute opening round and first-ever hardcourt victory against Flipkens, who returned to the tour last week in Chicago after six months off with an ankle injury.

The comeback snapped a seven-set losing streak for Garcia, as she'd lost her last three matches in straight sets dating back to the second round of the US Open.

"We've had a couple of battles in the past and from what I remember, every time, it was three sets most of the time. She started the match very well. She's coming from qualies so she's very confident, and for me, it's been a tough preparation," Garcia said.

"I was a little bit not feeling like myself, but I kept fighting on every point. I think really improved and the end of the first set, it was really close. The second set was going more my way but she kept battling, and I stayed more solid." 

With Garcia overcoming the one-set deficit (and minor wardrobe malfunction), she and Gauff, seeded No. 15 in the singles draw, will play for the first time.

While the Frenchwoman was sealing her victory, the 17-year-old American was also in action on Thursday, but with a partner by her side.

Gauff and her fellow teenager Leylah Fernandez, in their first matches since reaching the US Open doubles and singles finals, respectively, eased to a 6-1, 6-1 win over Irina-Camelia Begu and Renata Voracova in doubles action in Palm Springs.

Also coming from a set down to seal a second-round berth with a final-set bagel was Latvia's Anastasija Sevastova, who battled back against Polona Hercog in a 3-6, 6-2, 6-0 victory. The former World No. 11 will be the first opponent for No. 12 seed Ons Jabeur.

Golubic upsets Vondrousova, Trevisan outlasts Bouzkova in nearly four hours

To set a second-round meeting against No. 6 seed Maria Sakkari, Swiss No. 3 Viktorija Golubic earned just her second victory since a quarterfinal showing at Wimbledon: a 6-1, 4-6, 6-3 victory over Tokyo silver medalist and Chicago semifinalist Marketa Vondrousova.

While Golubic's win was just one of seven three-set matches to take place on Day 2, at just 1 hour and 52 minutes, it was not the longest. Martina Trevisan and Marie Bouzkova owned that distinction, as they battled for an incredible 3 hours and 52 minutes before the Italian qualifier was victorious, 6-4, 6-7(8), 6-4. 

Leading at 6-4, 4-2, Trevisan later failed to convert two match points in the second set tiebreak at 7-6 and 8-7 before ultimately wrapping up victory nearly 90 minutes after her first match point. The match is the second-longest of 2021 to date, and also the seventh-longest WTA main-draw singles match in the Open Era.

Read more: Marathon Marvels 2021: The longest matches of the year

The win extended a recent run of form for the 2020 French Open quarterfinalist, who's won 13 of her past 15 matches. She'll be the next opponent for No. 18 seed and Ostrava champion Anett Kontaveit.