Follow The Athletic’s French Open coverageWelcome to the French Open briefing, where The Athletic will explain the stories behind the stories on each day of the tournament.On Day 9, an unlikely quarterfinalist, the beauty of pressure in tennis and a long, slow comeback journey.How did a qualifier continue her dream run?If tennis fans are surprised to see 24-year-old Polish player Maja Chwalińska in the quarterfinals, after defeating the last French singles player standing at Roland Garros, they are not alone.“Well, it’s definitely a big surprise for me, and I didn’t expect it, surely,” Chwalińska said with a smile Monday after defeating Diane Parry.The world No. 114 came through three rounds of qualifying and has dropped just one set, to 2021 semifinalist Maria Sakkari, en route to her first career Grand Slam quarterfinal. She has far surpassed her previous best run at a major — the second round of Wimbledon in 2022.She took down the Olympic champion Zheng Qinwen, who was struggling physically, in the first round and upset No. 23 seed Elise Mertens in the second with her heavy topspin and deftness in the forecourt. After beating Sakkari in the third round and Parry, 6-3, 6-2 in the fourth, she is the first qualifier to reach the women’s singles quarterfinals at Roland Garros since Martina Trevisán in 2020.When she played Parry on Court Philippe-Chatrier, she made sure to take a picture of the plaque for Rafael Nadal that adorns the court first.“I’m really grateful for this opportunity,” Chwalińska said. “It’s such a beautiful court.“I knew coming in that it’s going to be a very tough match, you know, with the French crowd, as well, but they were very respectful, I think. They supported Diane, but me as well. I was very grateful for that.”Chwalińska isn’t one to take for granted the chance to play on one of tennis’ biggest stages. She took a mental health sabbatical from the sport in 2021 to manage a period of depression, and as a player outside the top 100, has had to deal this week with the logistical realities of an unexpected run in an expensive city.After her second-round match, she mentioned in her on-court interview that she was struggling to pay for a hotel in Paris because players don’t get paid — she’ll make just under $550,000 for reaching the quarterfinals — until after the tournament.She said later that the Polish company Oshee, which sponsors her compatriot and friend Iga Świątek, stepped up to help her out with accommodations. Chwalińska is hoping to extend her reservation at least a few more nights — she’ll face No. 22 seed Anna Kalinskaya next.— Ava WallaceHow did two matches underscore the beauty of pressure?If anybody needed a reminder of how different tennis is mentally when a player is ahead compared to behind, two fourth-round matches delivered Monday. First, Russia’s Kalinskaya and Russian-turned-Austrian Anastasia Potapova provided an exhibition in the afternoon.This was one of those matches when whoever was ahead would tighten up, and whoever was behind would relax and find their range, right up until Kalinskaya, the No. 22 seed, finally hauled herself over the line, 6-4, 2-6, 7-6(10-7).In the first set, the No. 28 seed Potapova started well and moved to a 4-1 lead. Then she promptly lost five straight games. to lose it 6-4.After Potapova won the second set in straightforward fashion, they moved into a decider. In the third set, Potapova went up a break three times, only to give it straight back each time — including twice when serving for the match. In between all that, Kalinskaya led 4-1, before she too got tight and gave up four straight games. Once into the tiebreak, it almost felt as though whoever went ahead would be at a disadvantage, and sure enough Potapova led 3-0 and 4-2 but faltered again with the finish line in sight.“It was a very mental match for both,” Potapova said in a news conference afterward. “Obviously it seems like for both of us it’s easier to play when you’re loose, because you kind of relax your body, and you just kind of let it go, and you don’t think about it.”Anastasia Potapova (pictured) and Anna Kalinskaya played a seesawing fourth-round match. (Anne-Christine Poujoulat / AFP via Getty Images)Kalinskaya has also had her issues in that regard, not just on Monday. She has never won a WTA title, and in the Berlin Ladies Open final two years ago, she missed five championship points before losing to Jessica Pegula. She joked in her on-court interview after beating her good friend Potapova that she had tried staying cool in the clutch moments, but had more less abandoned that policy as it clearly wasn’t working.“I was definitely nervous,” she said in a news conference.“The match was very physical. I felt like in third set I was up in the score 4-1. Then I saw she was a bit tired. At 4-1 I started to run out of energy to finish the match, and she was coming back, so that’s why the score was up and down a lot.”