Mattia Binotto has played down hopes that Ferrari's new engine for 2021 will be enough to catch Mercedes.
The Maranello team's boss said this week that early dynamometer testing of the new power unit has been "very promising".
"Currently, we don't have the best engine but next year we can have a completely new one," said Binotto.
The Italian warned that dyno limitations are forcing Ferrari to be "creative" with testing, but so far he is "happy with the results".
That triggered excitement that Ferrari's full recovery from a 2020 slump could be swift.
However, Binotto said: "Can we reach Mercedes? Perhaps that is asking too much since it means gaining between 40 and 50 horsepower.
"But being on par with Honda and Renault today would in itself be a remarkable step forward.
"We have to bear in mind that only one engine specification will be allowed for the whole of 2021, except for minor details. There is no room for error," he added.