The Woking-based team brought a big aerodynamic update package to Austria, which included a new short nose, front wing, floor and diffuser, but there were only enough parts for one car – and Alonso got the nod.

The double world champion said on Saturday that the upgrade had worked and further evaluation of the parts was planned for when Alonso returned to the wheel on Tuesday at the Red Bull Ring test.

But the damage caused by his first-lap crash with Raikkonen, which Alonso suggested featured a 40G impact, means McLaren will now run a mix of old and new parts.

The team has some spares, including the new nose box and compatible front wings, which will allow for a partial evaluation of the upgrade.

In light of the situation, McLaren has chosen to swap the driver line-up around, with Stoffel Vandoorne now kicking off the test on Tuesday and Alonso taking over on Wednesday.

Meanwhile, Red Bull has also tweaked its line-up with Pierre Gasly testing a day earlier and Daniel Ricciardo moving to Wednesday.