Welcome back to Clay Chronicles, where wtatennis.com will take a look back at some of the most memorable matches from the clay seasons of the past five years. After recapping Charleston's classics, our retrospective now heads to Stuttgart, Germany to recount some of the best matches from recent editions of the Porsche Tennis Grand Prix. Next up, World No.1 Naomi Osaka’s battle back from the brink against Donna Vekic in the 2019 quarterfinals.

Stuttgart Rewind:
2015: Angelique Kerber d. Maria Sharapova, second round
2016: Petra Kvitova d. Garbi?e Muguruza, quarterfinal
2017: Laura Siegemund d. Kristina Mladenovic, final
2018: Karolina Pliskova d. Jelena Ostapenko, quarterfinal

HOW THEY GOT THERE: Naomi Osaka soared to the top of the tennis world - and the WTA World No.1 ranking - at the start of 2019 when she tore through Melbourne to claim her second Grand Slam crown at the Australian Open.?

She promptly crashed back down to earth in her next match, falling in straight sets to an inspired Kristina Mladenovic in a Dubai opening-round stunner.??

Although Osaka avenged her loss to the Frenchwoman in her very next match, taking down Mladenovic in the second round of the BNP Paribas Open, the early losses continued into the Sunshine Swing. The Japanese player was upset by Belinda Bencic in the fourth round of Indian Wells, and lost out to Hsieh Su-Wei in the third round of Miami.?

2019 Stuttgart highlights: Osaka rallies to stun Vekic

Heading into Stuttgart, Osaka was still adjusting to the new target on her back that came with the World No.1 ranking, and admitted to feeling an added pressure to win every match she played.?

“I feel like I've dealt with the stress of people asking me if I have pressure because I have the No.1 next to my name. I thought I was doing fine with that, but I guess I'm not,” Osaka told press after her Miami defeat.??

“I think more about winning now compared to the matches before where I didn't necessarily think that was the case.”

Photo by Jimmie48 Photography/WTA

WHAT HAPPENED: Osaka again claimed her revenge against Hsieh in her Stuttgart opener, putting on a confident display to win 6-3, 6-3. The performance calmed the critics, but she was set to face an even bigger challenge in the next round against the rising Donna Vekic, ranked No.25 in the world.?

Their two hour, 18-minute contest was tight throughout, with both women converting on the lone break point available for either player as they split the first two sets, and then coming down to the wire in a third set tiebreak.??

Match report: Osaka rallies to stun Vekic in Stuttgart?

It was Osaka who drew first blood, breaking the Vekic serve in the sixth game and edging ahead to take the first set 6-3. But the Croatian player turned the tables in the next set,?staying toe to toe with the World No.1. Vekic broke in the 10th game after holding serve in the biggest battle of the match: a four-deuce battle where she had a total of five game points to keep Osaka at bay, 6-4.?

An increasingly frustrated Osaka seemed to have her foot halfway in the locker room as Vekic suddenly broke away, building up a daunting 5-1 lead. But the Australian Open champion never panicked, and never allowed the 22-year-old to reach match point despite serving for it twice. Osaka eventually claimed the victory in the tiebreak, securing a place in her first semifinal since winning the Australian Open, 6-3, 4-6, 7-6(4).?

Photo by Jimmie48 Photography/WTA

WHAT THEY SAID: Osaka herself was openly baffled by all the talk of a ‘slump’, especially considering she had reached the semifinals in Brisbane, won her second consecutive Grand Slam title, and was now into her first clay semifinal in Stuttgart.??

“Sometimes I hear people say, Naomi is kind of struggling there, and I’m like yo...." Osaka said with a grin. But Osaka also admitted that the criticism stung, especially considering the caliber of opponents she faced in her early defeats.??

Read more: Naomi Osaka hits back, preaches perspective after Stuttgart run?

"I would be lying if I said it wasn’t bothering me," Osaka said. "I tend to internalize everything, so it just builds up. I think you could tell so because I started getting really antsy on court compared to before. If I would make a mistake, I would react upon it. I feel that people that were really watching could tell.??

"I felt I wasn’t really enjoying myself. Like for me, when I play my best it’s when I have fun playing tennis and waking up every day with a new challenge. But during those few weeks, I felt like I was waking up wanting to win. I don’t think that’s a really good combo."

Photo by Jimmie48 Photography/WTA

Osaka stayed cool even as she found herself down 5-1 in the decider, and she pointed to her positive mentality as the key to her victory.?

"I feel like I try not to panic anymore because that takes up more energy and I don't really have that much energy to spare," Osaka said.?

"I just try to think logically and see how I can solve the problem."?

Photo by Jimmie48 Photography/WTA

WHAT IT MEANT: Unfortunately, Osaka’s Stuttgart came to an abrupt end just a few hours after her nerve-wracking comeback, as the Japanese player announced that she was withdrawing from the tournament due to an abdominal strain.??

But World No.1 quickly bounced back, and Osaka went on to reach four more quarterfinals between Stuttgart and the US Open, in Madrid, Rome, Toronto and Cincinnati. Heading into the year’s last Grand Slam, where Osaka was the defending champion, she was once again upset by Bencic and crashed out of the round of 16.??

The reigning Australian Open champion - now ranked World No.4 - was back to her full powers in the Asian Swing, and she ended her season on an 11-match winning streak. The Japanese player lifted the trophy in Osaka, the city of her birth, at the Toray Pan Pacific Open, and then went on to win her second Premier Mandatory title by defeating Ashleigh Barty in the Beijing final.?

?"It feels good," Osaka said in her champions’ press conference in Beijing. "For me, this was my goal. After I lost in the US Open -- I pretty much don't want to say I planned -- but I really meditated on it. It just feels like I accomplished what I set out to do."