Kamil Majchrzak stunned Felix Auger-Aliassime in straight sets to reach the Rosmalen Grass Court Championships semi-finals.

The world number four was the favourite to win the tournament in 's-Hertogenbosch, but instead crashed out as Majchrzak won 6-4 6-3 in just 70 minutes.

There was little to split the pair in the opening stages, with neither player giving up anything on serve, but Majchrzak finally got the vital break in the final game of the first set, converting his second attempt.

The Pole then went on another three-game winning streak in the second set, breaking Auger-Aliassime's serve in the sixth game, and there was no way back for the Canadian.

"This is definitely the best win of my career," Majchrzak said. "Felix has been at the top for a very long time.

"I knew what to expect. I knew I had to be at my best and be brave in the very big moments. I was very clinical. I was serving pretty well, and I was trying to maintain my [level] from the beginning until the end."

Majchrzak will be joined in the final four by former champion Alex de Minaur, who breezed past Benjamin Bonzi 6-2 6-4 in 69 minutes.

The Australian will face another former winner, Adrian Mannarino, in Saturday's match.

THE BIGGEST WIN OF HIS CAREER @LibemaOpen | #LibemaOpen | @KamilMajchrzakk pic.twitter.com/QUACmm5LWS

— ATP Tour (@atptour) June 12, 2026

Majchrzak serves up a treat

Majchrzak, ranked 76 in the world, claimed only his second top-10 win and is now through to his third ATP Tour semi-final and his first on grass.

While Auger-Aliassime was reaching the quarter-finals at Roland-Garros last week, Majchrzak was getting to grips with the grass courts, reaching the last four of a Challenger event in Birmingham.

And that extra bit of recent experience seemed to be a big help, especially on serve, as he lost only seven of 47 points (85%) and made sure he did not face a single break point.

As for De Minaur, he has found a lot of joy in the Netherlands in 2026, having already clinched the trophy in Rotterdam back in February.

He is now looking to become just the second player, after Richard Krajicek in 1997, to capture both Dutch ATP Tour titles in the same season, and with a 19-2 record behind him in the country, he will feel confident heading into the semi-finals.