June 13, 2025 • Tennis Analytics

's-Hertogenbosch Semifinals: Opelka vs. Bergs, Humbert vs. Diallo

Written June 13, 2025, about the events of that week. For today's numbers see the live Elo & Glicko rankings or who is moving now.

The grass courts of 's-Hertogenbosch are primed for big serves in semifinal action Saturday as four contenders vie for a spot in the Libema Open final. The matchups will feature American Reilly Opelka against Belgium's Zizou Bergs, and French second seed Ugo Humbert taking on Canadian Gabriel Diallo.

Here's a look at the semifinals:

Reilly Opelka vs. Zizou Bergs: An impressive run for lucky loser Opelka continues.
Ugo Humbert vs. Gabriel Diallo: Second seed Humbert faces a rising Canadian talent.
Recent Performances: Opelka stunned top seed Daniil Medvedev in the quarterfinals, showcasing 24 aces and zero double faults. Bergs also advanced by defeating Mark Lajal. Humbert is in strong form, dispatching Nuno Borges with relative ease. Diallo caused an upset by ousting third seed Karen Khachanov, marking his arrival in the top 50.
Outlook: Opelka's big-serving game on grass makes him a dangerous opponent, especially after his upset victory. Humbert's current form and grass-court pedigree make him the favorite against Diallo, who is having a breakout tournament on the surface.

Detailed Analysis:

Reilly Opelka vs. Zizou Bergs:

Reilly Opelka, reaching the main draw as a lucky loser, has reached the semifinals, highlighted by his straight-sets victory over top seed Daniil Medvedev. In that match, Opelka hit 24 aces and crucially capitalized on Medvedev's errors, particularly three double faults in the second-set tiebreak. This performance underscores Opelka's primary strength: a massive serve that is particularly effective on grass courts. Prior to this tournament, Opelka had a 1-4 head-to-head record against Medvedev. This will be Opelka's 16th ATP semifinal. His live ranking now is #75.

Zizou Bergs has also fought his way into the semifinals, overcoming Mark Lajal in his quarterfinal encounter. This marks Bergs' third ATP Tour semifinal of the 2025 season. After cracking the top 100 just over a year ago, he hit his all-time high ranking of 49 last month and could surpass that with a strong showing this weekend.

Opelka's serve and his win over Medvedev may give him a slight edge. Bergs' consistency this season and his multiple semifinals make him a capable opponent. The match could be decided by a few points, possibly in tiebreaks.

Ugo Humbert vs. Gabriel Diallo:

Second-seeded Ugo Humbert has had a smooth path to the semifinals. He cruised past Nuno Borges with a 6-1, 6-4 victory, showcasing his comfort and effectiveness on the grass. Humbert has yet to drop a set in the tournament, indicating his strong current form and suitability to the surface. His experience and seeding make him the favorite in this match.

Gabriel Diallo, on the other hand, is enjoying a breakout tournament. The Canadian caused a significant upset by defeating third seed Karen Khachanov 7-6, 6-4. This victory will see him break into the world's top 50 for the first time. Diallo's game, featuring a strong serve (19 aces against Khachanov), appears well-suited to grass, even though he had not secured a tour-level win on the surface before this week. He also saved match points in an earlier round against Jordan Thompson.

Humbert's experience, current form, and grass-court record make him the favorite. He has not dropped a set this week, while Diallo's powerful game could trouble him.