What happened: George Russell will start this weekend's Singapore Grand Prix with a grid penalty following his retirement in Sepang. The Mercedes driver stopped at the Turn 1 entry with five laps remaining while running third under the safety car. The power-unit failure requires an engine change for Marina Bay.

Why it matters: A back-of-grid start at Marina Bay puts Russell into recovery mode on a street circuit where track position decides points. It further hurts Mercedes after a difficult Sepang weekend and cedes ground in the constructors fight.

What to watch: Watch for confirmation of the power-unit elements and Russell's starting slot after qualifying.