Martin Whitmarsh has downplayed suggestions that Mercedes' 2014 V6 engine is the best in the field.
Next season will herald the arrival of the 1.6-litre turbocharged V6 engines which are taking the place of the V8s, which roared for the last time at this year's season-ending Brazilian GP.
And although the new engines have yet to be pitted against one another, there is speculation in the paddock that Mercedes have the edge over Renault and Ferrari.
For now, though, Whitmarsh, whose McLaren team will use Mercedes power for the last time in 2014, isn't making any predictions.
"Will we have a competitive drivetrain? I do not know," the McLaren team boss told Speed Week.
"There are many people in the paddock who seem to have much of a clue but I do not know what data they have to know that.
"From what I know about their resources and their organisation I'm assuming that they have done a good job and the resources have been used."
He added: "I believe that we will be competitive."