Haas dropped Esteban Ocon for the Mexico City Grand Prix. Reserve Ryo Hirakawa takes his seat.
Haas gave no reason for the move. It only confirmed that Ocon is not ill.
Ocon was angry at running medium tyres in Friday practice. He told his engineer not to do this to him.
Media reports claimed a physical clash with boss Ayao Komatsu. Ocon strongly denies any violence.
Ocon said a difference of views led to a talk. He rejects any claim of physical violence.
The Haas boss would not explain the call. He said only that Ocon is not ill.
Ryo Hirakawa, 32, is the reserve driver from Japan. He already drove Ocon's car in first practice.
Hirakawa qualified 19th. He is the oldest F1 debutant since Andre Lotterer in 2014.
Jenson Button said a tyre row in practice may have cost Ocon the rest of his F1 career.
Haas had already signed Rafael Camara for 2027. But teams almost never drop a driver mid-weekend.
No word yet on whether Ocon will race for Haas in Brazil. Autosport links him with an Aston Martin reserve role.
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