Red Bull advisor Helmut Marko believes it is only a matter of time before Mercedes is challenging for victories every week.
Mercedes has been off the pace of Red Bull and Ferrari this season but made clear progress with an upgraded car at the Spanish Grand Prix, although the team remained a clear third in Monaco.
Mercedes, winners of the last eight F1 constructors' championships, are quietly confident they can continue to cut the gap at the front as the development race ramps up over the coming weeks.
Marko shares that opinion and thinks Mercedes has shown flashes of huge potential.
"Mercedes is doing incredibly fast laps in practice and also in the races, both with [Lewis] Hamilton and [George] Russell," Marko told Formel1.de. "Not continuously, so for us it's difficult to interpret where that lap time is coming from. Listening closely to the Mercedes people, I don't think they know either.
"But the dangerous thing is the potential seems to be there. And once that can be called up over a race distance, then they'll be right up there or right at the front."
When asked if he felt like Mercedes was bluffing over its potential, Marko said: "No, it's not a bluff."
The F1 season continues with Baku's Azerbaijan Grand Prix on June 12.