'What the hell': Tennis world in disbelief over Rafael Nadal drama

Rafael Nadal admits his French Open preparations have taken a hit after the 20-time grand slam champion was stunned by Alexander Zverev in a straight sets quarter-final defeat at the Madrid Open.

The Spaniard admitted his 6-4, 6-4 loss to Germany's Zverev was a "step back" but insisted there were plenty of positives as he embarks on capturing a 14th Roland Garros title, later this month.

BRUTAL: Ash Barty's act of revenge as winning streak continues

'NEVER SEEN THAT': Ash Barty in bizarre incident in Madrid

'HELL OF A CHICK': Ash Barty's beautiful act for pregnant rival

The World No.2 has now fallen early in two clay-court Masters tournaments ahead of the Grand Slam in Paris, after going out in the Monte Carlo quarter-finals last month before winning in Barcelona.

Zverev had never beaten the 'King of Clay' on his favoured surface, but the 24-year-old was particularly impressive in the stunning upset.

Nadal's latest defeat on his favoured clay surface will surely serve as a blow to his quest for a record 21st grand slam singles title at the French Open - a tournament he's won an astonishing 13 times.

For Zverev it's now three straight wins against Nadal, with all three remarkably coming in straight sets.

Tennis world was understandably left gobsmacked the incredible turn of events.

"It's definitely one of the biggest wins of my career so far, especially on clay against Rafa," Zverev said.

"It is the toughest thing to do in our sport. Beating him in his house, in Spain, is incredible."

Zverev's impressive straights-set win at the Caja Magica earns him a meeting with Dominic Thiem in the semis, in what will be a repeat of last year's US Open final, which was won by Thiem.

After losing to world number eight Andrey Rublev in Monaco, Nadal was convincingly beaten by Zverev and the spotlight will be on the 34-year-old now in Rome next week, his last tournament before heading to Paris.

"I took steps forward, but when you go up a staircase, there are times when it happens that you take a step back, that's what happened today," said five-time Madrid champion Nadal.

"It's a week where there were a lot of positive things. I'm leaving Madrid with good feelings in general, and the bad one having played a match like today.

"Now, what is the goal before Roland Garros? Go to Rome (for next week's Italian Open) and win, that's all."

Zverev sets up Thiem semi-final showdown

Nadal had been hoping to reach the semi-finals of a Masters event for the 75th time.

"I had the match under control at the beginning and was playing well for six games, probably playing better than him," said the Spaniard.

"Then at 4-2 serving for 5-2, I had a disaster."

It started well for Nadal when he broke Zverev to love to lead 4-2 in the first set, Zverev serving a double fault to give away the first advantage.

But the world number five immediately hit back and then pulled away, four straight games clinching him the set.

A whipping forehand down the line put Zverev up another break midway through the second and while Nadal resisted more pressure in the seventh game to hold, Zverev served out an impressive victory after an hour and 44 minutes.

Thiem had earlier come from a set down to beat 36-year-old John Isner of the United States 3-6, 6-3, 6-4 and reach the last four.

Norway's Casper Ruud reached the semi-finals of a claycourt Masters event for the third successive time by beating Alexander Bublik of Kazakhstan 7-5, 6-1.

Ruud, who knocked out world number five and Monte Carlo Masters champion Stefanos Tsitsipas in the previous round, will face Matteo Berrettini for a place in the final.

Italian world number 10 Berrettini defeated Chile's 25th-ranked Cristian Garin 5-7, 6-3, 6-0.

with AFP

Watch 'Mind Games', the new series from Yahoo Sport Australia exploring the often brutal mental toil elite athletes go through in pursuit of greatness:

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.