Zizou Bergs defeated Reilly Opelka 6-1, 6-4 in the semi-final of the ATP 250 event at 's-Hertogenbosch on grass on 14 June 2025, delivering a significant upset against the pre-match favourite. Opelka entered the match as the odds-on favourite at 1.69, but Bergs proved the superior player on the day, winning both sets with relative comfort and breaking down the American's serve-reliant game on the quick surface. The Belgian's dominant performance, particularly in the opening set, demonstrated his growing confidence on grass courts and his ability to compete against higher-ranked opponents in this format. Bergs advanced to the final and will look to build on this momentum, while the result represents a notable setback for Opelka's grass-court campaign.