What happened: Ferrari fitted a new power unit to Lewis Hamilton's car after he was hit by a mechanical issue in final practice at the São Paulo Grand Prix. The team removed the unit from car No. 44 for checks following FP3 and opted for a complete replacement ahead of qualifying.

Why it matters: Hamilton entered Saturday already facing a 10-place grid penalty after exceeding the season limit of four engines. The setback compounds Ferrari's chase in the constructors' standings, where the team trails Mercedes by 126 points.

What to watch: Hamilton will run in Saturday qualifying to establish his baseline track position before grid penalties are applied for Sunday's race.