The McLaren boss believes the Woking-based outfit is still a work in progress and that realistically, wins will remain out of reach this season, but Alonso is keeping his hopes up.
"I read what Zak Brown said, but who knows?" Speed Week quoted Spaniard Alonso as responding.
"I am keeping a positive attitude, preparing for the championship as intensely as ever, and I will do everything in my power."
Indeed, the two-time title winner has stepped up his efforts this winter given the expectation that Formula 1's new cars will take their toll on any driver physically unprepared.
Alonso's routine includes a workout in the gym, 50 kilometres of cycling per day and over 5kms of daily running.
"Ninety per cent of the drivers on the grid have only driven an F1 car that is slightly faster than a GP2 car, but I have driven cars that we will never see again.
"If we are going to improve a few seconds this year maybe it will be similar, but I don't think it will radically change the physical requirement," Alonso said.
Regardless of where McLaren's performance will be this season, Alonso still believes that Mercedes remain once again clear favourites.
"Surely Mercedes are on a trajectory to lead having won the last three world championship as they have done.
"Then Red Bull will adapt well to the new rules, but we will have to see how we all adapt. We really do not know still. F1 is always an unknown, but this year that is even more so."