Red Bull advisor Helmut Marko was surprised Mercedes allowed Nikita Mazepin to show their "superiority" during the Barcelona test.

After race driver Valtteri Bottas had posted a 1m15.5s on the C5 Pirelli tyre on Tuesday, the Russian, in his first appearance with the team, was only 0.2s slower a day later.

It was a time which created an interesting reaction, with many saying it proved how easy the current Formula 1 cars are, but Marko had a slightly different view.

"That a second-rate Formula 2 driver can set the fastest time right off the bat driving the Mercedes shows how superior Mercedes is. More superior than ever," GPFans.com quoted him as telling AutoBild.

"What surprised me… that Mercedes did not try to play with hidden cards and did not prevent Mazepin from driving the best time so that the superiority is only really clear."

The Red Bull chief has previously admitted he expects Mercedes to dominate next weekend's Monaco Grand Prix, a race his own team usually targets for victory.

And he reiterated that belief again while also making a damning prediction about Ferrari.

"Although Mercedes has the longest wheelbase, their lead there will be even bigger, they're true traction monsters, that's the nuts and bolts of Monaco," Marko said. "We've found something, but it's not enough.

"If Ferrari cannot generate downforce and traction, they'll probably only finish sixth or seventh in Monaco," the Austrian suggested.

"Their weakness was evident in the last race in Barcelona, which is most reminiscent of Monaco. Their engine is very good but they lacked downforce and extreme traction."