Fellow German Vettel saw the best opportunity to dethrone the dominant Brit since in 2018, but a series of team and driver errors meant the Ferrari man faded away as Hamilton marched on to his fifth Championship.
Rosberg highlighted how Vettel works tirelessly with his engineers, something he claims Hamilton doesn’t do, and that mental strength is the final ingredient to get the job done.
Speaking to Autosprint, he said: “Vettel is superior in terms of dedication to work; he works closely with the engineers.”
“It is a devotion that Lewis Hamilton does not have.
“I do not know exactly what happened to him [Vettel] but this is sport, sometimes it seems everything is going in the right direction, then you just need one mistake to bring you down, you lose confidence and everything goes wrong.
“The same thing happened to me against Hamilton in 2015. With Lewis, I needed to change my attitude, I decided that I had to be the one to lead the game.
“Lewis always tends to impose his rules but I took control so as not to allow him to find the motivation. And I won.”
Rosberg also believes Vettel should take new team-mate Charles Leclerc seriously, stating he will need to be “perfect” to beat the 21-year-old.
“Vettel will have to beware because Leclerc is very strong and he will no longer have the comfort zone of Raikkonen,” Rosberg explained.
“Now it will be different, Seb will have to be perfect if he wants to win.”