Engine change for both Ferraris
Earlier, the Italian team said Felipe Massa had a precautionary engine change on Sunday morning because "abnormal parameters" were detected.
Each driver is allocated just eight engines for the entire 19-race season, although Ferrari said the Bahrain qualifying engines can be used again in free practice sessions.
"The mechanics are working incessantly to complete the replacement (on Alonso's car)," said the team.
In other pre-race news, it has emerged that both HRTs will start from the pitlane after the struggling new team worked on the cars overnight during the 'parc ferme' period.
Ross Brawn is back at the circuit after feeling unwell on Saturday.
Drivers are expected to make just one (mandatory) tire pitstop on Sunday, with Williams' Sam Michael briefing the media on Sunday morning that 2 stops require too much overtaking.
The first leading pitstops are expected to take place around lap 15, with Adrian Sutil probably able to stay out for longer after qualifying tenth on the harder tire.
Michael Schumacher and Alain Prost were late for a photograph of the many world champions present this weekend in Bahrain.
They were photographed separately and will be added to the shot with the help of Photoshop.
03/14/10 (GMM) Felipe Massa will start Sunday's season opening Bahrain grand prix by using his second official engine.
Each driver is allocated a maximum of eight engines for the entire 19-race calendar, whereafter grid penalties begin to apply.
"Not the best start of the day," a Ferrari official said on Sunday morning, explaining that the engine change is "precautionary". He said the removed engine will be used again in practice sessions later this season.
A statement added that the engine he used in qualifying showed "some abnormal parameters".
Brazilian Massa is on the front row of the Sakhir grid with pole sitter Sebastian Vettel.
Saturday night also saw the start of a new 'parc ferme' procedure in F1, with cars zipped up in flyscreen-like covers in their garages.