McLaren's Carlos Sainz has opted to go with a fresh new power unit ahead of final practice for the Spanish Grand Prix.

While the team is still facing cooling issues, McLaren will be hoping for better results from the car itself.

Back at Silverstone last weekend, the Spaniard failed to explain why the cooling issues that held him were still hampering his performance at his home Grand Prix even though they had changed a host of parts including the chassis and admitted they are "starting to run out of things to try".

After that, the next steps were to change the power unit fully, with McLaren opting to fit a fresh Renault internal combustion engine (ICE), turbocharger, MGU-H and MGU-K ahead of the final practice session at Barcelona on Saturday before the showdown race on Sunday.

This is also the first time Sainz has changed any of those components, so he can do so penalty-free.

However, Carlos is not the only one with a new engine as Haas' Romain Grosjean also opting to go for a fresh power unit ahead of the Spanish GP.

A huge day of qualifying coming up on both sides of the Atlantic today. Let's do this, team!  @ArrowMcLarenSP #SpanishGP  | #Indy500  pic.twitter.com/VYMWAngxeg

— McLaren (@McLarenF1) August 15, 2020