Alexander Blockx, a 21-year-old Belgian ranked 69th in the world, has produced one of the surprises of the tennis season at the Madrid Open, defeating defending champion Casper Ruud 6-4, 6-4 on Thursday to advance to the semi-finals. The result is all the more remarkable given that Blockx only entered the main draw at the last minute, after a string of late withdrawals pushed him up from the qualifying rounds just before the deadline.
Blockx's run through the draw has been relentless. He has dispatched seeded players including Brandon Nakashima, Félix Auger-Aliassime (ranked fifth in the world), Francisco Cerúndolo (20th), and now Ruud (15th) — a Norwegian who reached the Roland Garros final in both 2022 and 2023 and whose best surfaces are widely considered to be clay. In the quarter-final, Ruud fought back from 2-4 down in the first set to level at 4-4, but Blockx ultimately wore him down. In the second set, facing three consecutive break points at 3-3, Ruud saved himself to 30-40 before a stunning Blockx backhand ended the game. Blockx squandered two match points in the following service game but closed out the match on his own serve.
The conditions at Madrid's Caja Mágica arena — built on an elevated plateau roughly 650 metres above sea level — have suited Blockx particularly well. "It's clay, so it's slow. I have time for my shots. But because of the altitude and the heat, it's also fast. The perfect combination for me," he said. The thinner air at altitude causes the ball to travel faster and bounce lower than at sea level, rewarding heavy servers; Blockx recorded a remarkable 80% effectiveness on his first serve during the run.
Blockx came into 2025 having reached the title match of the Next Gen ATP Finals in December, a prestigious end-of-year event for the sport's top young players. He had modestly projected a top-40 ranking by 2026, but his Madrid campaign has already propelled him into the virtual top 35, making him the highest-ranked Belgian on the ATP Tour. "I never thought I'd get this far. But once you get confident and feel your game, a lot can happen," he said.
In Friday's semi-final, Blockx faces Alexander Zverev, the second seed and world number three from Germany. A win would push the Belgian into the top 30. The other semi-final sees world number one Jannik Sinner of Italy take on France's Arthur Fils.