Monday was a busy day in WTA 1000 Mutua Madrid Open, as all the round of 16 matches got played in Caja Magica venue to set up the full line-up of quarterfinals. It was definitely a day of surprises, as 5 out of 8 matches ended up with a victory of the players who were not rated as a favorites related to pre-match odds.

The biggest surprise of the day is undoubetly the win of Petra Martic, who made a big upset over Barbora Krejcikova. The Czech was rated as a clear pre-match favorite with an odd 1.20. Martic was surely not a player to write off here, as she has already proved her great clay court skills, winning two WTA level tournaments on this surface in the past. The Slovenian was on the front foot from the start of both sets, gaining an early break advantage. Krejcikova was able to level the score in both cases, but the tournament's 27th seed prevailed to regain her advantage in relatively quick first set, and overcame the comeback of her higher rated opponent in 79 minutes long second set ended up in tiebreak. A few last games of this match were really entertaining, as Martic had two breakpoints within Krejcikova's serve in 9th game. The Czech cleared the danger well and broke her opponent to level the score in the following game. Krejcikova was very close to force the decider, as she produced 4 setpoints in 12th game during Martic's serve. The Slovenian denied all of them and made a crucial hold, after which she dominated the second set tiebreak. It was surely the most important game of this clash, as it could turn over in possible deciding set after the waste of initial chances to close this match by Martic.

Iga Swiatek will play against the Slovenian in the quarterfinal after the late-night match against Ekaterina Alexandrova. Despite being a banker favorite ahead of this match, it was definitely not a cakewalk for the Pole, who was surprisingly took into the whole distance by the world's number 17. The Russian started this match well with a break in opening game, but Swiatek regrouped well and took this set with a score 6-3, needing just one breakpoint in both 6th and 10th game. The world's ranking leader raised up the pace and run away with a score after the start of 2nd set, leading with a break advantage and having a chance to serve for the match in 9th game. The Russian has surprisingly broke back and leveled the score in the following game despite defending a breakpoint which was the first matchpoint for Swiatek at once. Whole the set was settled in tiebreak, where Alexandrova started with a minibreak and took care of this advantage till the end, winning 7-3. Swiatek denied the huge upset in third set, raising up her level and being well composed during own service games. 6-3 with double break and no single breakpoint to defend in third set was a way to advance into QFs in quite an unusual match which has ended up after 1:00 AM local time.

Jessica Pegula and Veronika Kudermetova set up possibly the most intriguing pairing of the QFs. Pegula was a clear favorite ahead of the match against Martina Trevisan, but the Italian showed that she is publicly known as a clay court specialist not without a reason. Trevisan forced Pegula to fight for the quarterfinal spot in three sets, but the world's number 3 managed to prevail in quite a dynamic match with a score 6-3 2-6 6-3. Veronika Kudermetova reached out the QFs after third three-setter in a row. Just a one day after 3-hours long battle against Anastasia Potapova, the 12th seed eliminated another fellowcountry Daria Kasatkina. It was no shorter and no less thrilling battle, than the one against Potapova, as Kudermetova won 7-5 1-6 7-6(2) despite defending 2 matchpoints in 12th game of deciding set within own serve.

There are no home crowd's favorite remaining in the field at the stage of quarterfinals in Madrid, as Paula Badosa got eliminated by Maria Sakkari in relatively quick two sets match which ended up after 89 minutes with a score 6-4 6-4 for the Greek. Badosa was definitely a hope for the Spanish fans to make a significant run on the home soil after good performances on clay in Charleston and Stutgart and great dominant win over Cori Gauff in previous round. This time, the current world's number 9 was too strong for Badosa, as Sakkari showed an ultimate performance in a high quality match played from both. The Greek was defending just 2 breakpoints in 4th game of the match and after successful hold there, she was in no trouble during service games till the end of match. Sakkari broke Badosa to love in 7th game which occured to be decisive in opening set and built the crucial advantage in opening game of 2nd set, as she earned the break there and held all the serves till the end. Irina Camelia Begu will be Sakkari's opponent in the quarters. The Romanian continues her brilliant run in Madrid, approaching the QFs without losing a single set so far. Begu defeated the tournament's 14th seed Liudmila Samsonova in straight sets today, and same as Sakkari earned the advance with a score 6-4 6-4.

The sensational run of the 16 years-old Mirra Andreeva got stopped by Aryna Sabalenka. The world's number two gave no much chances for the young Russian, as she scored a confident 6-3 6-1 win, finishing the match in just 73 minutes. It was quite a contention just after the start, as both players shared breaks in two opening games, but Sabalenka dominated whole the play since the score 2-2, winning 10 out of 12 remaining games.

Mayar Sherif celebrates her career's best results on the level of WTA 1000 tournaments, as the Egyptian reached out the quarterfinals for the first time after defeating Elise Mertens in a long three-sets battle. Sherif crossed the line with a score 6-4 0-6 6-4 after 2:52 hours of play. It was really shaky match from both, as 15 out of all 29 games ended up with breaks. Sherif performed quite an unusual achievement, winning the match with this kind of stake despite being broken in 8 out of 13 games. The world's number 59 regrouped really well after getting a bagel in second set and prevailed in open battle against higher ranked Mertens in the deciding set.