Most of the drivers took the opportunity to test out the conditions on intermediate tyres as rain fell during the final hour of practice in Barcelona on Saturday morning. 

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But Hamilton decided against running on the wet-weather tyres, something that Rosberg - who pipped the seven-time world champion to the world title in 2016 before retiring from F1 - questioned. 

"Look, now Lewis is in a rush to get his belts on because he was out of the car,” Rosberg said during Sky’s coverage. 

"I think Bradley [Lord, Mercedes communications director] should have had a word with him.

"Maybe this is Bradley, that's why Lewis is back in the car.”

Having revealed he had spoken to Mercedes after the session, Rosberg added: “Lewis could have perhaps made a little bit of a better effort in FP3 and been out there more to learn a bit more. 

“It was in fact his decision to be in the garage for all that time and to also go out a bit late on the softs. So they [Mercedes] did say it was perhaps not 100 percent ideal. 

“But then again, as a seven-time world champion you could allow yourself to do that.” 

Hamilton showed potential signs of improvement for Mercedes after a difficult opening day of practice by ending FP3 third behind the two Red Bulls. 

The Briton, who admitted at the end of Friday that he feared for his top-10 chances in qualifying, was just over four-tenths shy of Max Verstappen’s benchmark.