The Spaniard failed to complete a single flying lap in the session as his car was confined to the garage while mechanics worked on finding a solution.

Alonso will get a grid penalty if McLaren decides to use a new power unit rather than reverting to an old one.

Future hopes

Although Honda took the decision to bring its upgrade to Belgium, Jenson Button said on Thursday that the true extent of its benefit would not really be felt until races later in the year.

“It is a good little boost, which is nice,” he said. “It is not going to move us up the grid I would say, only because this was always going to be a tricky one for us.

"I think it will probably leave us in the same place as Hockenheim, which is still positive, and probably the same at Monza.

“When we get to the circuits like Singapore it will probably give us a bigger boost than circuits like here – well, not a boost, but not have the negatives that we do at a circuit like here. I am looking forward to it.”