Damon Hill believes Mercedes could be "stuck" behind Red Bull for the foreseeable future despite finding gains at the Spanish Grand Prix.
The Silver Arrows recovered a less-than-ideal qualifying to finish second and third behind Grand Slam winner Max Verstappen and surpass Aston Martin in the Constructors' Championship.
The upturn in form comes after Mercedes brought a fresh design to their car at the Monaco GP to be more in line with Red Bull's concept.
But even though these updates appear to have worked, Hill thinks they will always be behind Red Bull based on the design of the W14's chassis.
Lewis Hamilton has been all smiles since Mercedes changed their technical direction in Monaco
Unlocked more potential
"Maybe this has unlocked more potential," Hill said on the Sky Sports F1 podcast. "But whether it's able to unlock more potential to beat Red Bull is questionable because I think they are stuck with the fundamental chassis they have underneath [the car].
"To hear Lewis say 'I'm enjoying driving the car'. That's a good sign and an indication for him because he's been saying, 'I told you we should have done something earlier'.
"They have gone and done what he has been pleading with them to do and they have seen some progress, so well done Lewis."