Alexander Zverev is out of the BMW Open after a shock straight-sets defeat to Holger Rune in the last 16 in Munich.

The world number three and top seed had no answer to an impressive performance from Rune, with the young Dane ultimately easing to a 6-3 6-2 victory on Wednesday.

Rune set the tempo early on, moving Zverev around the court with plenty of drop shots and heading into a 4-2 lead, before saving two break points on his way to clinching the first set.

An early break in the second then seemed to give the 18-year-old the confidence to see out his first career victory against a top 10 opponent.

"It was a difficult match from the beginning," said Rune on-court after the win. "He's in the top three in the world and has been playing some unbelievable tennis, especially in the past year winning so many big titles.

"I have a lot of respect for him, and I obviously didn't expect to win in two sets, and with a score like this. But it was a really hard match, we played a lot of rallies and I'm really happy about my performance today."

Rune will play Emil Ruusuvuori in the quarter-finals after the Finn beat Maxime Cressy 6-3 6-3.

Elsewhere, fourth seed Nikoloz Basilashvili came from behind to overcome Ilya Ivashka 3-6 6-2 6-4, and will face Miomir Kecmanovic in the last eight after the seventh seed beat Daniel Altmaier 6-2 6-4.

There were also three round of 32 matches on Wednesday, with eighth seed Botic van de Zandschulp, Egor Gerasimov and Alejandro Tabilo all through to the last 16 in Munich.

Over at the Estoril Open, Alejandro Davidovich Fokina will play Frances Tiafoe in the quarter-finals after both advanced in Portugal.

Fourth seed Davidovich Fokina beat fellow Spaniard Bernabe Zapata Miralles 6-3 7-6 (7-5) while fifth seed Tiafoe got the better of Nuno Borges 7-6 (7-4) 4-6 6-0.

Fernando Verdasco is also through after a 6-2 6-3 win against Pablo Cuevas, and he will play fellow Spaniard and sixth seed Albert Ramos-Vinolas, who came from a set down against Kwon Soon-woo, 5-7 6-1 6-2.

Stefanos Tsitsipas defended his Monte Carlo Masters crown and lifted his eighth ATP Tour title by defeating Alejandro Davidovich Fokina in straight sets on Sunday.

Greek Tsitsipas, who defeated Andrey Rublev to triumph in Monaco last year, eased past second seed Alexander Zverev in the semi-final and repeated the trick with a 6-3 7-6 (7-3) victory over Davidovich Fokina.

The Spaniard beat Novak Djokovic and reigning Indian Wells Masters champion Taylor Fritz en route to his maiden ATP Tour final, and started well on Court Rainier III with an early break.

However, Tsitsipas found his rhythm with his ferocious forehand to break back before winning four of the next five games to take the lead.

The world number five, appearing in his fourth Masters 1000 final, then failed to serve out for the match at 5-4 up in the second set, but recovered in the tie-break to secure his first trophy of the season.

In doing so, Tsitsipas becomes the sixth player to manage consecutive Monte Carlo titles in the Open Era, while half of his eight tour-level titles have come on clay.

"I am very proud of myself," Tsitsipas said in his on-court interview. "Things weren't going well at one point, but I managed to stay composed to finish the match off.

"I am really proud with the belief I put in my game. Sometimes you doubt yourself, but it is always important to keep your head high."

Davidovich Fokina was aiming to become the first unseeded champion in Monte Carlo since Thomas Muster in 1992, and Tsitsipas acknowledged the 22-year-old made him fight to reclaim the trophy.

"He fought in moments I didn't expect him to fight," Tsitsipas said. "He can hit incredible winners out of nowhere and play unpredictably.

"But I was able to minimise that. I knew he would be a dangerous opponent but that is a great win for me. I think we will see great results from him in the future."

Stefanos Tsitsipas remains on course for a second consecutive Monte Carlo Masters title after recording a straight-sets semi-final win over Alexander Zverev.

The third seed, who defeated Andrey Rublev to clinch the title in Monaco last year, produced a scintillating performance to beat the world number three 6-4 6-2 in Saturday's last-four encounter.

Tsitsipas will face world number 46 Alejandro Davidovich Fokina in Sunday's final, and the Greek said he will need to perform at an even higher level to defeat the 22-year-old, whose incredible run continued with a three-set win over Grigor Dimitrov in the final four.

"It was good," Tstispas told Amazon Prime Video of his semi-final win. "I don't know whether the long match [his three-set quarter-final win over Diego Schwartzman on Friday] gave me some rhythm, but I was able to play good tennis today. I'm happy with the level I was able to execute, and I came up with some good ideas on the court.

"I'm looking forward to the next one, I have a difficult opponent tomorrow, so I need to be ready and to take the best out of this one and move on.

"It's going to take a little bit more [to beat Davidovich Fokina], he's in a good rhythm. I've played him before, and he's a difficult opponent, I'm going to be as ready as possible, he's definitely improved and I'm going to have to produce the best tennis I can."

Davidovich Fokina, who has made headlines by eliminating Novak Djokovic and Indian Wells Masters champion Taylor Fritz during a thrilling run in the municipality, beat Dimitrov 6-4 6-7 (2-7) 6-3 earlier on Saturday, reaching his first ATP Tour final.

The unseeded Spaniard needed two hours and 43 minutes to wrap up his semi-final contest, and revealed that a bathroom break allowed him to reset his mind and clinch a hard-fought victory after he failed to serve out the second set at 5-4 up.

"I am so happy to be in the final, it's a dream come true to try to have the title," he said after the win.

"When I was a kid, I was dreaming about this day and it's come true, I'm so happy.

"In the second set I had my chances, I was so tight. But I went to the bathroom [after the second set] and I said to myself 'I want this'. Now I am in the final, I will enjoy, I have all the power with me."

Reigning Monte Carlo Masters champion Stefanos Tsitsipas will have to overcome Alexander Zverev if he is to have the chance to defend his title.

Zverev, who is ranked third in the world - two places higher than Tsitsipas - fought back to defeat Jannik Sinner 5-7 6-3 7-6 (7-5) in his quarter-final match, denying his opponent another top-five seed scalp following his prior win over Andrey Rublev.

"It means a lot, definitely, especially [with] how this year has been going so far for me," said Zverev after a gruelling three hours on court.

"I've lost long matches like that, so I’m happy I won this one."

Tsitsipas also orchestrated a superb turnaround against Diego Schwartzman, prevailing 6-2 6-7 (3-7) 6-4.

The Greek had looked set for a last-eight exit at four games down in the final set, only to stage a dramatic comeback to keep his hopes of a first title since last May's Lyon Open alive.

"There was a moment in the match where I felt what I was doing wasn't working," Tsitsipas said.

"He had a massive lead and momentum in what he was trying to do. I just tried to stay in the match as much as I could and that worked out very well.

"I wasn't expecting much at that point being a double break down, so I relaxed at that point."

Schwartzman meanwhile will rue his inability to put the tie to bed, having already reached two ATP finals this year.

Grigor Dimitrov and Alejandro Davidovich Fokina will face off in the other semi-final.

Bulgarian Dimitrov beat off Hubert Hurkacz in another final-set tie-break, winning 6-4 3-6 7-6 (7-2).

Fokina, who eliminated Novak Djokovic in the second round, turned over Indian Wells champion Taylor Fritz in another comeback result, triumphing 2-6 6-4 6-3.

Alexander Zverev and Stefanos Tsitsipas progressed to the quarter-finals of the Monte Carlo Masters with straight sets wins on Thursday, remaining on course for a final meeting.

Last year's runner-up Andrey Rublev, however, missed out on a last-eight spot after falling to a three-set defeat against Jannik Sinner.

World number three Zverev overcame Spain's Pablo Carreno Busta 6-2 7-5 to progress in Monaco, where he is seeking to win the sixth ATP 1000 title of his career.

"For the second clay-court match of the season, I can't complain too much," the 24-year-old second seed said on court after sealing the victory.

"Yes, I lost focus a little bit in the second set, but at the end of the day, he's somebody that can really play. I'm happy with a two-set win."

Tsitsipas (3) remains in contention for a second consecutive title in the principality after defeating Laslo Dere 7-5 7-6 (7-1) and will face off against 12th seed Diego Schwartzman for a semi-final spot after the Argentine defeated Lorenzo Musetti in a hard-fought three-set encounter.

There will be no repeat of 2021's final between Tsitsipas and Rublev, however, after the Russian fell to a thrilling 5-7 6-1 6-3 loss to ninth seed Sinner in the day's final contest.

The other seed to fall victim to a shock in the last 16 was world number seven Casper Ruud, losing 6-3 7-5 to Grigor Dimitrov, who will face Poland's Hubert Hurkacz in the last eight. 

Finally, Novak Djokovic's conqueror Alejandro Davidovich Fokina cruised past David Goffin 6-4 6-1 to set up a quarter-final tie with the United States' Taylor Fritz, who bested compatriot Sebastian Korda – with whom he played doubles with in Monte Carlo – in straight sets.