Sebastian Vettel's Ferrari is being fitted with his fourth and final penalty-free engine for this campaign following troubles in final practice.
Vettel was second quickest in Saturday's third practice for the Malaysian Grand Prix, finishing 0.162s down on his team-mate Kimi Raikkonen.
However an issue late in the session curtailed his running as he dramatically slowed to limp back to the Ferrari.
The Scuderia have diagnosed an electrical issue and, in order to avoid further problems, have opted to fit his SF70H with a new power unit.
The engine, reportedly an upgrade on what he was running earlier in the weekend, is his fourth and final penalty-free power unit for the season.