Red Bull Racing remain in the dark as to why Sebastian Vettel suffered several reliability issues during last weekend's Australian GP.
Vettel was unable to challenge at the front during Saturday's qualifying due to an engine software issue and lined up 12th on the grid.
His problems, though, went from bad to worse on Sunday when his Renault engine dropped a cylinder, putting the reigning World Champ out of the race.
But why Vettel's RB10 was the sole Red Bull hit with problems remains a mystery to team boss Christian Horner.
"It looks like it dropped a cylinder for whatever reason, and we need to understand exactly what has caused that - whether that is through electrical or software or whatever," he explained to Autosport.
"From Saturday morning with Seb, the power unit put up a real fight and there was no logical reason for it.
"The settings are the same [as on team-mate Daniel Ricciardo's car], both fresh engines going in.
"But it shows how finely things are poised at the moment."
Horner, though, did reveal that Ricciardo had one minor glitch before the start of Sunday's race but that it was easily resolved.
"We had a drama when he left the garage as the turbo did not work," said Horner.
"We had to get the car back in to reset the power cycle, and it seemed to come back to life.
"So there was a drama as we were going out to the grid, but that fixed itself and didn't reappear."