(Photo credit: Jayne Kamin-Oncea-Imagn Images)

Alexander Blockx won 84.8% (28 of 33) of his first-serve points and stormed his way to a 6-4, 6-4 upset of defending champion Casper Ruud on Thursday to reach the semifinals of the Madrid Open.

Blockx, 21, from Belgium, needed just 96 minutes to dispose of Ruud, the No. 12 seed from Norway. Ranked No. 69 in the world, Blockx is the fourth-lowest ranked player to reach the semis in Madrid.

'To be honest, I'm just happy with being here,' said Blockx, who upset No. 3 seed Felix Auger-Aliassime of Canada and No. 16 Francisco Cerundolo of Argentina earlier in the tournament. 'Even winning my first match here. I barely escaped in the first round, and I was happy about that already. Semifinals is something I wouldn't have even dreamed of to begin with.

Blockx will face No. 2 seed Alexander Zverev of Germany in a semifinal on Friday. Zverev defeated No. 10 Flavio Cobolli 6-1, 6-4 in his quarterfinal match.

Blockx said the clay surface is challenging but also very much to his liking.

'I'm proud of how I've played these past couple of matches,' Blockx said. I think the conditions suit me well here. I feel like it's clay which is slow, so I have time to settle and hit my shots, go for my shots. At the same time, it's quite fast with the altitude and the heat sometimes. I think it's the perfect combination for me.'

Both players scored 19 winners, but Blocks had just 16 errors, seven fewer than Ruud.

Meanwhile, Zverev outpowered Cobolli with a 12-1 edge in aces and by winning 82.1% (32 of 39) of his first-serve points while prevailing in 90 minutes.

Zverev also had a 23-11 advantage in winners while earning his 179th career clay-court victory, most among Germans in the Open Era. He broke a tie with Philipp Kohlschreiber.

Zverev, a two-time Madrid champion (2018, 2021), lost to Cobolli in straight sets on April 18 in the Munich semis. Cobolli lost to Ben Shelton in the final of that event.

The rematch unfolded a lot differently on Thursday.

'No revenge. I love Flavio. He's one of my favorite guys on Tour,' Zverev said. 'I have a great relationship with him and a great relationship with his father. This is sport. ... Sports can change very quickly. In Munich, he played an amazing match and I didn't play a very good match. Today, it was maybe the opposite.'

Cobolli saved 8 of 11 break points but committed four double faults.

Top-seeded Jannik Sinner of Italy and No. 21 Arthur Fils of France square off in the other semifinal.

--Field Level Media