Thursday's action in Stuttgart emerged the line-up of Porsche Tennis Grand Prix quarterfinals, which will be played tomorrow. All the top four seeds are still in contention after winning their round of 16 matches. Iga Swiatek came back to compete on the highest level after the injury which eliminated her from taking part in Miami Open and Billie Jean King Cup qualifiers. Swiatek started the campaign on her favorite clay surface from not the easiest challenge, facing Qinwen Zheng as the first opponent to play against after one month of absence. It was no issue for the Pole though, as she showed a dominant performance, winning first set 6-1 after just 33 minutes of play. Second set also started well for the world's number one, but the Chinese managed to fight back, scoring her first break this afternoon, by converting the only one breakpoint produced throughout whole the match. Swiatek responded quickly, retaking the lead in the following game and secuirng the victory a while later with final score 6-1 6-4.

"I felt like I needed to be 100% focused from the beginning to the end, to think about technique and tactics. I am pretty happy that I am not rusty and I could perform good tennis, even though I had a break. Qinwen is really talented, and everybody can see that. I needed to adjust, and I am just happy that I was focused on myself, on what I wanted to do and I feel pretty comfortable, so I am happy that I could show my good tennis." - said the Pole in her post-match interview.

Karolina Pliskova will be the next Swiatek's tomorrow. The Czech, who eliminated Maria Sakkari in first round while showing a great performance, was a pre-match favorite against Donna Vekic. The former world ranking's leader proved her good form in first set, winning it 6-2. Second set was another story, as the Croatian raised up her level and was leading with a break twice, but whole the set was ended in tiebreak. Vekic was on the front foot again there, winning a tight 13th game 7-5 and forcing a decider. Third set was a display of great serving performance from both players. Vekic has defended the only two breakpoints in this set, making an important hold in 5th game. All the rest games ended up even without a necessity to play on deuces. Whole the match was settled in another tiebreak which was no less tight battle than the one played in second set. All the last 5 points were being lost by the serving player, but it was Pliskova who had a margin of mini-break in her tally and converted third matchpoint, winning it all with a score 6-3 6-7(5) 7-6(5).

Anastasia Potapova scored her fourth career's win against top 10 player and second in a row against Cori Gauff, eliminating the 5th seed after a comfortable 6-2 6-3 win. Both players approached the round of 16 after tough opening matches, ended up in three sets. Gauff was a pre-match favorite, but the American was looking quite off today. The American made 53 unforced errors in general, making the job quite easier for Potapova, who played really well today, dominating the match from the start. The Russian was putting a pressure well, creating 13 breakpoints and converting 3 of them. The world's number 6 was not without chances today, as she created 6 chances, but today's winner was clinical in crucial moments and cleared all the danger.

Caroline Garcia will play against Potapova in Friday's quarterfinal. The world's number 5 was a clear favorite ahead of the match against home player Tatiana Maria and she managed to take it in straight sets, but some effort was needed in both sets. The French did not convert any of 4 breakpoints in 10th game during her opponent's serve and could even lose the opening set while getting broken in the following game. Maria did not manage to serve for the set though and Garcia snatched the win in this set after tiebreak, ended up with a score 7-5. Second set has also brought a good chances for the home favorite, as Maria was leading 3-0 up with a single break advantage. It was not enough to push whole the match into distance though, as Garcia broke her opponent 3 times in a row and secured the win with a score 7-6(5) 6-4.

Paula Badosa gave no chance for her fellowcountry Cristina Bucsa in the clash of two best ranked Spanish racquets. Badosa, who is seemingly coming back to a very good form, scored the 5th win in her 6th clay court match this year, defeating the fellowcountry 6-1 6-2. The next opponent will be much more demanding for the Spaniard, as she faces her good friend, current world's number two - Aryna Sabalenka.

Beatriz Haddad Maia advanced into quarterfinals after the withdrawal of Elena Rybakina who pulled out during second set of the match against the Brazilian. Rybakina, the second best player in this year's WTA Race ranking, was a favorite before the interesting match-up against Haddad Maia, but the world's number 14 was dominating almost from the start. The Kazakh won her first service game easily and produced 3 breakpoints in second game, which was in line with the pre-match expectations. Then, Haddad Maia started to fully dominate the on-court action, snatching first set by winning 5 games in a row. Rybakina took the medical time-out after 3 games of second set. After losing the serve in following game, the reigning Wimbledon champion withdrew from the match, clearly suffering some injury issue. Ons Jabeur will be the opponent of Haddad Maia in Friday's quarterfinal.