Ahead of this weekend's race in Bahrain it emerged that Sainz would need to move onto his second MGU-K following the early failure he suffered in the race in Melbourne.

However, the FIA confirmed at the start of the first free practice session at Sakhir that McLaren has made a host of changes.

As well as the new MGU-K, Sainz switches to a second internal combustion engine, turbocharger and MGU-H of the season.

Drivers are allowed to use two MGU-Ks all season and three of the other components McLaren has changed for Sainz in Bahrain.

If drivers need more components beyond those limits, they will incur grid penalties.

It is not yet known if the parts McLaren have changed can be repaired and added back into the pool of useable components, or if Sainz has taken a big step towards a grid drop later this year.

On Thursday, Sainz highlighted the weakness of the MGU-K, which had been problematic during pre-season.

"It is true we had a couple of failures during testing, so it is something that is a weak point of the car," he said.

"We need to keep working on to ensure we don't throw any more points into the bin because we did throw a couple of them in Australia."

The rest of the grid is yet to make any power unit element changes so far this season.