Sebastian Vettel wants to show Ferrari that the Italian team made "a huge mistake" by deciding to drop him.
That is the view of Gerhard Berger, the F1 legend who was the eventual quadruple world champion's first team boss at Toro Rosso back in 2008.
Berger told f1-insider.com that he could sense Vettel was back to top form last weekend in Hungary.
"Sebastian seems to be completely free in his head again, as if he wants to prove to Ferrari that not extending his contract was a huge mistake," he said.
"Also, with this bad car, he no longer has the pressure that he absolutely must win. In Hungary he was the old Vettel again. Leclerc didn't stand a chance," Berger added.
Berger now thinks Vettel, 33, should accept an offer to join the Aston Martin project for 2021.
"Nothing against Sergio Perez and Lance Stroll," he insisted, "but a Sebastian Vettel would drive to be runner-up world champion this year in that year-old Mercedes."