Umpire Brian O'Nora exited the Cubs‑White Sox matchup after a foul ball struck him in the fourth inning. The ricochet came off a 93.1 mph fastball from Jameson Taillon and bounced off O'Nora's mask before hitting his neck. Jarred Kelenic’s foul ball forced a medical pause as the White Sox cited concussion‑like symptoms. He briefly knelt before being examined by trainers.

After O'Nora’s removal, crew chief Erich Bacchus shifted from second base to behind the plate, leaving the game with three officials. Play resumed without further incident, and the Cubs held on to a 5‑4 victory that kept them within striking distance of the NL Central lead. The incident sparked a brief delay but did not alter the final score.

The league’s health protocol will now review O'Nora’s case, as any concussion concerns could sideline an experienced umpire for weeks. Chicago’s staff praised the quick assistance from Miguel Amaya and the White Sox trainer, emphasizing player‑safety culture. Meanwhile, both clubs remain focused on the race for postseason berths, with the Cubs eyeing a wild‑card spot as this schedule tightens.