Sauber team principal Monisha Kaltenborn says she has "no doubts" over the progress Ferrari has made with its 2016 engine.
The Hinwil-based team benefited greatly from the step Ferrari made with its power unit ahead of the 2015 season, scoring 36 points after a disastrous points-free 2014 campaign despite little work being done on the chassis throughout the year.
The works Ferrari team also took a big stride in the championship, finishing second in the standings, notching up three wins and 16 podium finishes.
And the progress made by the Italian outfit means Kaltenborn is bullish of her own team's prospects for the new season.
"I am confident, they [Ferrari] have already shown in 2015 the step they took," she said.
"You can’t expect miracles, the gap [to Mercedes] is so big that you have to take it step-by-step, and you also have to look at the reliability.
"But I think they have done a very good job, and I have all reasons to have no doubts, or rather to have the belief that they are going to take the next step."
No Mercedes-like advantage
However, Kaltenborn thinks that the gap between the Mercedes-powered teams and the others is too big for Ferrari to be able to surpass the German manufacturer.
"I think the teams which had the Mercedes engines in the first year, when this engine [formula] came in could have a bigger benefit then you could have now," she said.
"Because simply the other teams were so far back, and that’s already closer. So yes, there can be a benefit, but definitely a smaller one than that time, because the differences are no longer so big.
"If Ferrari were to make that kind of step where they are couple of seconds away from the rest, then you could compare it to that, but that kind of advantage we are not going to have," she concluded.