Max Verstappen has matured over the winter.
"Max is still very young, but mature," he told Algemeen Dagblad newspaper.
"I already noticed it during the Barcelona tests. In other years he thought testing was boring and saw it as a chore, but this year I saw enthusiasm and concentration."
Verstappen has also been accused of impetuousness in the recent past, but Marko adds: "We will also see a patient Max this year, who understands that he cannot win all the races.
"Without that (approach), you will not become a world champion."