Honda is still struggling to get to the bottom of the latest reliability issues which have hit McLaren's drivers in Bahrain.
Stoffel Vandoorne suffered a power unit failure on Friday and Fernando Alonso was forced to abort a qualifying in Q2 yesterday when his engine suddenly lost power.
While Honda has traced the problems to the unit's MGU-H which harvests energy through recycled exhaust gases pressured by the turbo, the cause of the failure remains undetermined.
"We are not sure the exact cause, but definitely a mechanical failure of the MGU-H - something around the bearings was sticking and it happened three times here," explained Honda engine boss Yusuke Hasegawa.
"It was very unfortunate. We are not sure why it has happened just here three times. But we suspect something has happened in this circuit or environment or characteristics.
"Possibly because the temperature is very high and the conditions are very sandy, but we don't know the cause."
With some parts beyond repair, the failures have seriously eroded Honda's inventory of authorized parts, just three races into the 2017 season!
Vandoorne has now used three of his four allocated turbos and MGU-H components, while Alonso's McLaren MCL32 will be fitted with an entirely new power unit for Sunday's race.
"Fernando will use a new MGU-H and Stoffel also a low-mileage one, so I think we will be alright tomorrow."
Grid penalties are sure to kick in sooner rather than later for McLaren, compounding its problems in what looks like another season to be written off for the Woking-based outfit.
GALLERY: All the pictures from Saturday in Bahrain
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