Ferrari team principal Fred Vasseur was hospitalised ahead of Saturday's qualifying at the Monaco Grand Prix.
Vasseur, 58, was on hand Friday when Ferrari's two entries topped the practice sessions for the Formula 1 race.
Ferrari confirmed that Vasseur would miss Saturday's critical qualifying day for unspecified medical reasons.
"Following some medical checks, Fred will remain under observation at a local medical facility. No further medical information will be provided," the team's statement said. "We wish Fred a speedy recovery and look forward to seeing him back at the track soon."
Ferrari drivers Lewis Hamilton and Charles Leclerc are both looking for their first win of the season on Sunday.
Through five races, Leclerc ranks third and Hamilton fourth in the F1 drivers' standings. Ferrari trails leader Mercedes in the constructor standings.
Vasseur replaced Mattia Binotto as team principal at Ferrari ahead of the 2023 season. Before that, the Frenchman held the same position at Sauber/Alfa Romeo (2017-22) and Renault (2016).
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