Charles Leclerc says Ferrari have made "quite a good step" with their 2021 car but admits it is too early to say how well they can perform.
Ferrari had their worst season for 40 years in 2020, but the team have worked hard on fixing their main weakness, which was speed on the straights.
Leclerc said: "There has been a lot of work. We have been pushing quite a lot.
"It always looks positive on paper but then we need to see what the others have done as a step."
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The 23-year-old was speaking at the official launch of the Ferrari team before the new season, alongside new team-mate Carlos Sainz and team principal Mattia Binotto.
Ferrari struggled last year with an engine that was down on power after they reached a confidential settlement with governing body the FIA, who believed the 2019 engine was not always legal, but could not prove it. On top of that, the car had too much drag.
Binotto has always denied Ferrari broke the rules with their engine in 2019 but has admitted its performance was affected by a series of rule clarifications before the 2020 season.
Ferrari have built a new engine for 2021 with the aim of eradicating its weaknesses.
Binotto said: "The main issue was the straight-line speed last year - not only power but power and drag. We have worked a lot on the power-unit and the aerodynamics to reduce the drag. And based on what we can see we recovered quite a lot of speed on the straights.
"I am expecting the speed not to be as much of an issue as it was. I hope we can be competitive but we believe it is certainly more efficient, both from the aero and power-unit point of view."
The new car, the SF21, was not revealed at the launch - it will break cover on 10 March, two days before the start of pre-season testing in Bahrain.
Binotto said: "We know we need to do better in 2021. What will count more is our will to win. I am not saying we will win. We have to be realistic - there have been cars that are very strong last year and with the cars partially frozen will be very strong again in 2021.
"But will to win is our commitment, our intention, being aware that details count, determination will be important and showing progress. That is what I am expecting."
What do the drivers expect?
Leclerc is ensconced as Ferrari team leader after two highly impressive seasons in 2019 and 2020, in which he out-performed his former team-mate, the four-time champion Sebastian Vettel.
The Monegasque said he had fully recovered from catching coronavirus in Dubai over the winter and had been working hard on improving his performances further this season.
"Covid did not hit me that bad," Leclerc said. "I did some physical tests to make sure everything came back to normal and that is the case.
"I have never been in [the] Ferrari [factory as much] as before this season. We have been doing quite a bit of tests with the old car. I feel very ready.
"I have been working in a similar way as in the past, trying to understand what were my weaknesses last year.
"I still believe tyre management is something I should push. I improved a lot last year and I hope there will be another step this year."
Leclerc said he was expecting a respectful relationship with Sainz, who joins Ferrari after two seasons at McLaren.
"It is very clear we need to push for the team," Leclerc said. "Carlos wants to beat me and I want to beat him too. We will try to be careful when we fight each other on track.
"What is most important is we separate what happens on the track and off the track. It is a fine line that every team-mate needs to find. Carlos is very competitive but he is also here for the benefit of the team, as I am, and we will have to play it smart on that one."
Sainz said he expected to find it "difficult" to beat Leclerc in his first season at Ferrari as he finds his feet.
But he added: "In five years, my target is to be world champion. I believe Ferrari is the right place to achieve that. We just need a bit of time to make it happen."
What about sprint races?
F1 has agreed in principle to try out shorter sprint races on Saturdays at three races this season as a way of setting the grid for the grand prix.
Both Ferrari drivers cautiously welcomed the plan, as long as it did not diminish the value of the main race on Sunday.
Sainz said: "Until we try it, we will never know. It is super-important the grand prix does not lose value. It is a bit dangerous that sometimes there can be two winners out of a grand prix weekend and we need to make sure there is only one winner. But if there is a year to try it, it is 2021."
Their thoughts echoed those of Red Bull drivers Max Verstappen and Sergio Perez when they were asked about the topic on Thursday.
Binotto said Ferrari supported the idea in principle but that the details of the plan were still being worked out.
The 2021 season begins with the Bahrain Grand Prix on 28 March.
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