Ferrari have changed the engine of both F10 ahead of Sunday's Bahrain GP but stressed that they were just a "precautionary" measures.
Felipe Massa is making his return to competitive racing in Bahrain this weekend and qualified an impressive second place on the Sakhir grid.
The Brazilian finished just 0.141s behind Red Bull's Sebastian Vettel and three-tenths up on his double World Champ team-mate Fernando Alonso.
However, after examining the telemetry from the power unit overnight, Ferrari opted to change it on Sunday morning.
"At 10am, when the FIA rules allow to work on the cars, the mechanics started to work on the F10 number 7, replacing its engine," the team said in a statement.
"This is a completely precautionary step: the engine, used by Felipe Massa up to the qualifying yesterday afternoon shows, some abnormal parameters, but can still be used on the track, according to the applicable rules, during free practice sessions.
"The decision, taken last night, will not lead to any sanctions for the Brazilian driver, who will start from the first row."
Meanwhile, Ferrari confirmed hours later that his team-mate Alonso had also been given a new power unit.
"We will change the engine on Alonso's car for the same precautionary measure which determined the previous decision," said a statement on Ferrari's Twitter feed.
