After an impressive first campaign for Ferrari in 2019, Leclerc is determined to do an even better job this year to become a regular contender for wins and even the title.
Having made notable progress in lifting his qualifying potential over the course of last season, he says the key area for now is doing better on Sundays.
Speaking exclusively to Motorsport.com in a podcast about where he had made the biggest gains and what next he needed to focus on, Leclerc said: "After the first three four races, I've seen that my weakness was more the qualifying than the race.
"So I focused quite a lot on the qualifying and did quite a big step from France onwards in qualifying, which was good to see.
"And then in the race I think I've still got quite a bit of work to do. Seb has a big experience in the race and he's stronger than me at the moment. So my work this winter is mostly on the race, to try and improve that."
Leclerc thinks it essential too that both he and Ferrari cut out the kind of mistakes that cost them several victories last year – especially in the early stages of the season.
"I hope, or at least I'm working extremely hard, to do less mistakes than I've done in 2019," he said about prospects for the year ahead. "I think as a team, we also need to focus on that.
"In terms of performance it is always very, very difficult to know before the first race. Actually I was going to say winter testing, but actually in 2019 winter testing went a lot better than the first race. So we will wait for the first race.
"But we've been working well, and then to see the performance we'll see a bit later on. But I feel definitely more ready than at the beginning of 2019. And I hope I'll be able to prove it on track."
The battle between Leclerc and Vettel will be a fascinating one this year after their rivalry boiled over at times in 2019 – most famously when they crashed into each other at the Brazilian Grand Prix.
But while Leclerc accepts there are times when the pair do not see eye-to-eye, he is clear that their relationship off track is much better than it appears.
"I think we are mature enough to understand that whatever happens on track, obviously we are two competitors," he said. "We both want to win and it would be wrong if it will be the other way around.
"So yeah, we want to win. We are extremely competitive and sometimes on track we might have some frictions, but at the end, we are mature enough to know that what's happened on track is on track and off track, we are different persons.
"I think the most important [thing] is that we work well together, especially off track to try and develop the car in the best way possible. And, of course, not exceed the limits whenever we are on track, like we've seen in Brazil. But I think it was a good lesson for both of us and it won't happen again."
For the full interview with Charles Leclerc, listen to the latest Autosport Podcast