Colapinto will become the first Argentine driver to compete in F1 in over two decades this weekend in Monza after replacing struggling Logan Sargeant for Williams.
His appointment delighted fans of the sport back home, but asked whether he felt like football icon Messi before the last World Cup, Colapinto said such talk was "crazy".
"It's very difficult to feel as Lionel Messi, I don't know how it is to feel that," Colapinto told reporters.
"But sometimes I see that they compare me and I'm like, you guys are crazy, like Messi is God, it's like you cannot, how are you comparing me?"
Colapinto hasn't set high expectations for his debut with Williams, who have a paltry four points in the F1 constructors' championship.
"I am not expecting much... I just want to go step by step, I want to focus on myself," he added.
"That's the main thing I think. To be able to be focused on my job. To be able to do what the team expects. And I am, to be honest, more than sure that I can do it."
The action gets underway at Monza on Friday with the first two of the weekend's three practice sessions.
