MONACO - Formula One rivals hope to discover some of dominant Red Bull's most closely guarded secrets from photographs of the underside of Sergio Perez's car after it was craned off the Monaco Grand Prix circuit.

The floor is the most aerodynamically sensitive area of the car, with ground-effect sculpting responsible for much of the performance.

It is also the hardest part for rival teams to get a glimpse of, unless a car overturns or is lifted into the air -- as Perez's was after the Mexican crashed into barriers in Saturday qualifying.

Monaco marshals typically use cranes to clear stranded cars from the metal-fenced track because of the close confines and lack of runoff.

"With these regulations, the most important bit is the bit you don’t normally get to see," Mercedes trackside engineering director Andrew Shovlin told reporters on Sunday.

"So the teams will be all over those kinds of photographs. Monaco is a good opportunity to get that kind of shot."

Mercedes also had Lewis Hamilton's newly-upgraded car hoisted high into the air, giving a good view of the underside, but Shovlin said Red Bull -- winners of every race this season with four one-two finishes -- would be more annoyed.

Aston Martin performance director Tom McCullough said the exposure of the wooden plank, which every Formula One car has running down the middle of the floor, would also provide useful information.

"You learn a lot from just even how the plank is wearing. You learn from what’s touching," he said. "There’s a lot of very excited aerodynamicists up and down the pitlane looking at all of that."

Mercedes team boss Toto Wolff joked on Saturday that the crane operator must have been trained by the "Cirque du Soleil", so high was Hamilton's car lifted and at such an angle.

"That was suboptimum for us, to say the least," added the Austrian.

(Reporting by Alan Baldwin, editing by Ed Osmond)