Fernando Alonso has criticised Ferrari team boss Marco Mattiacci after the Italian unfavourably compared him to Sebastian Vettel.
Mattiacci said Vettel, who is replacing Alonso at Ferrari, "will bring the enthusiasm needed to go through certain difficult moments that are waiting".
Alonso, who is leaving after five years at Ferrari, said: "I heard the comments and I don't think they were very good.
"If he tried to mean I was not motivated, he arrived too late."
Double world champion Alonso has finished second in the championship three times in the past four years, twice losing out at the last race, despite driving an inferior car.
Alonso has outscored his team-mates - Felipe Massa from 2010-13 and Kimi Raikkonen this season - by significant margins in all those years.
Alonso added of Mattiacci: "He's only been here for a few months and has not seen the five years that I've spent here and how I've fought every single race."
And the 33-year-old made a sarcastic reference to his negotiations with Ferrari about the end of his contract.
"Probably I was too old when he tried to renew me until the Monza race (in September), and he kept pushing and pushing and having talks, and even in the last moment we had a lot of phone calls and emails that I still have in my computer.
"Probably at that time I was not so old, but when I took my decision I guess he had to find another driver."
Alonso is to join McLaren, who have not yet confirmed their driver line-up and say they will not do so before 1 December.
The team are trying to decide whether to retain Jenson Button or Kevin Magnussen alongside Alonso.
Mattiacci's future at Ferrari is in doubt after reports emerged that he will be ousted imminently after just seven months in the role.
Mattiacci joined Ferrari in April following the resignation of former team principal Stefano Domenicali.
The company is said to have lined up as his replacement Maurizio Arrivabene, the vice-president of global communications at Philip Morris International, the team's main sponsor.