MADRID -- After spending more than three hours on the court and earning a hard-fought victory, Rafael Nadal was feeling optimistic again.
Nadal's body withstood its toughest test yet at the Madrid Open as he needed three sets to get past 91st-ranked Pedro Cachin on Monday.
Nadal didn't show any signs of physical limitations as he won 6-1, 6-7 (5), 6-3 to make it to the round of 16 at the clay-court tournament where he is the record five-time champion.
"It's positive, now I don't feel that something went wrong on my body, but I need to wait until tomorrow, being 100% honest," he said. "I am trying my best to keep dreaming. Tomorrow is another day to keep dreaming. To keep playing in front of this amazing crowd and, to me, that means everything."
Nadal will next face 31st-ranked Jiri Lehecka. He said he needs "to find a way to be able to play days in a row and still be competitive."
"I don't know if I am in that moment yet," the 22-time Grand Slam champion said. "Let's see what can happen tomorrow. But I going to try. I going to do the things the right way to try to be ready for tomorrow."
The 37-year-old Nadal is trying to get in shape for next month's French Open. Since his latest injury layoff, he's had two matches in Barcelona and was pessimistic about his physical condition after arriving in Madrid. But he's won three more times in the capital.
Nadal again looked comfortable early on against Cachin. The Argentine fought back in the second set but was broken twice while serving for the set. Cachin eventually prevailed in the tiebreaker.
Nadal didn't look as loose in the final set, but did look tired. He wasn't as consistent with his shots but picked up three breaks to seal the victory to the delight of the local crowd in the Caja Magica.
"I took more risks in the third set, but it's hard after so many months without competing," Nadal said. "I hadn't played a match like this in a long time. Let's see how it goes tomorrow. I don't know how I'm going to wake up. But I'm already happy for having won three matches in a row."
Cachin asked for Nadal's shirt after congratulating him at the net, and received the gift moments later.
Top-seeded Jannik Sinner was not at his best but had enough to defeat Pavel Kotov 6-2, 7-5. Sinner, who has been dealing with a hip issue, will face 16th-seeded Karen Khachanov.
"I have been struggling a little bit with my right hip," Sinner said. "We're trying to find a solution and I don't think it's anything serious. Sometimes I feel it more like today and some days are a little bit better."
Daniil Medvedev came from behind to defeat Sebastian Korda 5-7, 7-6 (4), 6-3. The third-seeded Russian was two points from defeat.
Fifth-seeded Casper Ruud beat Cameron Norrie 6-2, 6-4.
Also, Madison Keys rallied after trailing in the first and second sets to defeat Coco Gauff 7-6 (4), 4-6, 6-4 in an all-American fourth-round meeting.
It will be the 20th-ranked Keys' first quarterfinal appearance in Madrid. She lost in the first round in seven of her nine previous trips to the Spanish capital.
The third-seeded Gauff undermined herself with 38 unforced errors, including 13 double faults.
Keys will face eighth-seeded Ons Jabeur, who eased past Jelena Ostapenko 6-0, 6-4.
And top-ranked Iga Swiatek remained on track for a first Madrid title by dispatching Sara Sorribes Tormo 6-1, 6-0.
Swiatek dropped just five points in the second set en route to the quarterfinals of the only major European clay tournament the Pole has yet to win.
The 27th-ranked Sorribes Tormo was the last Spanish woman in the draw.
Swiatek, who lost last year's Madrid final to Aryna Sabalenka, will next face 11th-seeded Beatriz Haddad Maia, who defeated fifth-seeded Maria Sakkari 6-4, 6-4.
Sabalenka, the champion in Madrid in 2021 and 2023, advanced by beating No. 15 Danielle Collins 4-6, 6-4, 6-3. The result ended Collins' 15-match winning streak, and sent Sabalenka into her first WTA 1000 quarterfinal of the season.
Mirra Andreeva celebrated her 17th birthday with a 7-6 (2), 6-4 win over 12th-seeded Jasmine Paolini. The teen sensation from Russia came from 5-2 down in the first set to reach the quarterfinals, a round further than she managed in Madrid a year ago.
Fourth-seeded Elena Rybakina defeated teenage qualifier Sara Bejlek 6-1, 6-3.