Motorsport's governing body is enforcing a new rule change, beginning at this weekend's Spanish Grand Prix, that potentially could have major ramifications for leaders McLaren, and world championship front-runners Oscar Piastri and Lando Norris.
From this weekend until the end of the season, the FIA is tightening the restrictions on the flexibility of every car's front wing.
The new testing is reducing the deflection allowance of the front wing by 5mm, in a move described by Ferrari team principal Fred Vasseur as a "game changer".
On an F1 car, all aerodynamic parts of the bodywork, except the DRS flap on the rear wing, must be immobile and rigid.
To be specific, Article 3.2.2 of the sport's technical regulations states:
"All aerodynamic components or bodywork influencing the car's aerodynamic performance must be rigidly secured and immobile with respect to their frame of reference … Furthermore, these components must produce a uniform, solid, hard, continuous, impervious surface under all circumstances."
However, there have been rumours that some teams have been able to exploit this rule.
By coincidence, the discussion about some teams having flexible wings came to the fore following last year's Spanish Grand Prix, when it was becoming clear that McLaren had caught the previously dominant Red Bull in performance.
Last year, McLaren's rear wing was causing a stir with teams believing it was not conforming to regulations. The FIA tightened up the rear wing regulations at this year's Chinese Grand Prix.
Now the focus is on the front wing, which has also caused some consternation in the F1 paddock.
To put it simply, some believe teams may have manufactured a front wing that could deform under aerodynamic load at high speeds.
That aerodynamic force allegedly could change the shape of the front wing to reduce drag on the car. The wing could then snap back into its original shape when the car slows down, maximising downforce through corners.
Starting this weekend, the FIA will introduce a tougher test on front wings.
The previous test would apply a load of 1,000 Newtons (around 100kg) in a downward direction on two points of the wing.
The wing was allowed to deflect up to 15mm when the force was applied to each side of the wing, and 20mm when applied to just one side. The new testing reduces these deflection allowances to 10mm when force is applied on both sides, and 15mm when applied on one side.
The FIA announced the front wing clampdown at the start of the year, giving teams until the Spanish Grand Prix to have front wings that will conform to the new testing requirements.
Whether the more rigid front wings will have any effect on F1's pecking order will be closely watched this weekend in Barcelona.
"This can be a game changer for everybody because we don't know the impact on every single team of the new regulation," Vasseur said during the Monaco Grand Prix weekend.
McLaren drivers Piastri (161 points) and Norris (158 points) are the top two in the drivers' championship standings after eight rounds, with Red Bull's defending world champion Max Verstappen (136 points) the only other driver to mount a challenge so far.
McLaren's team principal Andrea Stella at the start of the season told UK broadcaster Sky Sports that McLaren would need to make adjustments to conform to the new front wing regulations, but insisted in February that is would not be a "headache".
"We don't have to make many adjustments at all for the start of the season. There will be a small adjustment required from race nine," he said.
The time for adjustments has come, with McLaren the team with most to lose if they have been able to exploit F1's front wing regulations for the past two seasons.
