Jenson Button has acknowledged the possibility that McLaren might not be on the pace early in the 2011 season.
The MP4-26 has been hailed as the bravest of the new class of 2011, but Button and Lewis Hamilton have not strongly featured on the timesheets as reliability problems slowed development work.
"I have definitely not completed the laps that I expected to," Briton Button is quoted by Italy's Autosprint, "and when it comes to developing a new car it is essential to do a lot of kilometres."
The 2009 world champion added: "This car has a lot of potential, but if the development work is late, there may be a gap in the first races of the championship."
Autosprint said the nervousness of the MP4-26's handling was visibly obvious at the recent Barcelona test, particularly in comparison to the field-leading Red Bull.
"Barcelona is a track that rewards aero balance," said the Italian report, "but this does not seem to be the only front on which McLaren must direct its efforts."
The final test of the pre-season takes place next week, again at Barcelona's Circuit de Catalunya.
"It will be an important test," acknowledged Button, "for putting everything together, but I think it will be very difficult to get an exact idea of the hierarchy.
"I've heard rumours that the Red Bull is six tenths faster than Ferrari, and also that Ferrari are one second faster than everyone on race pace!" he is quoted as saying.
"I think that to get an overall picture we will have to wait until the first race," added Button.