Alexander Zverev remains confident of a third Madrid Open title but acknowledged he would have to beat the "incredible" Flavio Cobolli to get there.

Zverev booked his quarter-final date with the Italian following a hard-fought victory over Jakub Mensik on Tuesday, prevailing 6-4 6-7 (4-7) 6-3 in the Spanish capital. 

The second seed controlled the opening set after a break of serve in the first game, but an evenly-contested second went in Mensik's favour to force a decider. 

However, Zverev was able to regain his composure to reach the quarter-finals, reeling off five of the last six games as he concluded a two-hour-and-18-minute epic on serve. 

With his win, Zverev, along with world number one Jannik Sinner, are the first pair to reach the quarter-finals at each of the first four ATP Masters 1000 events of the season since Roger Federer and Rafael Nadal in 2011.

They could face each other in the showpiece match, but standing in Zverev's way is Cobolli, who beat Daniil Medvedev in a three-set thriller of his own earlier in the day. 

"Incredible [improvement]. He's a very streaky player, but when he plays well, he plays really well. And he [has] shown that the last couple of weeks," Zverev said of Cobolli. 

"He made the final in Munich, quarter-finals here now. I do feel like if I play well, if I play good tennis, I will have good chances, and I have to trust myself."

The third of his career overall, Cobolli has claimed more ATP top 10 wins this month than in his career prior. The Italian was 1-16 against ATP top 10 opponents coming into this year's European clay swing, though he will face a stern test against Zverev here. 

Zverev has won two of his three meetings against Cobolli at ATP level, though the 10th seed did win their last meeting on clay in the Munich Open semi-finals earlier this month. 

Cobolli can reach a maiden career ATP Masters 1000 semi-final and his fourth at ATP level overall in 2026 after Delray Beach, Acapulco and Munich. 

He could also defeat multiple ATP Masters 1000 champions at a single Masters event for the first time in his career, while Zverev can reach a 27th career semi-final at ATP Masters 1000 events, trailing only Novak Djokovic (80) among currently active players for Masters semi-finals appearances.