Seven-time world champion Lewis Hamilton was disqualified from Friday's qualifying session at the Brazilian Grand Prix after a technical infringement by Mercedes in the latest blow to the British driver's defense of his Formula One title.
The stewards' decision forces Hamilton to start Saturday's sprint race at Interlagos in last position.
Hamilton and Mercedes can appeal the decision.
On a dramatic pre-race day, Hamilton's rival, Red Bull's Max Verstappen, was fined after the Dutch driver was seen touching the rear wing of the Mercedes car.
The sprint race will determine the grid for Sunday's main race in which Hamilton will start at best in sixth due to a separate five-place penalty for Mercedes changing the car's engine in Sao Paulo.
Verstappen leads Hamilton by 19 points in the standings with four races left this season.
Hamilton beat the Dutchman by more than 0.4 seconds in qualifying for the sprint race, but organizers said that his Mercedes was under investigation for DRS exceeding the maximum distance when opened. The technical infringement typically leads to exclusion from a session. The decision was only announced after Saturday's practice session, and before the sprint race.
"It was clear to the stewards that the additional deflection was due to additional play either in the DRS actuator or the pivots at the end, or some combination or other fault with the mechanism, or incorrect assembly of the parts," the decision said. "There is therefore no question in the minds of the stewards that the test failure indicates any intent to exceed the maximum dimension either by action or design."
The decision also says Mercedes argued that the rear wing design had passed FIA's tests several times during the season and had always been approved. Mercedes denied having any intent to breach regulations.
Hamilton's disqualification will put Verstappen in pole for the 24-lap sprint race, which offers three points to the winner. Mercedes' Valtteri Bottas will move to second position, while Red Bull's Sergio Perez will be third. AlphaTauri's Pierre Gasly will inherit the fourth place on the grid.
Earlier, Verstappen was fined 50,000 euros ($57,200) by stewards after video taken from the grandstands at Interlagos showed him touching the rear wing of rival Hamilton's car.
The Dutchman can appeal the decision given by the stewards, who said he did not harm his competitor's car with the touch.
The video recorded by a spectator shows Verstappen apparently inspecting the rear wing on the Mercedes in the Parc Ferme — a secure area for cars at the track.
"Considering the fact that no direct harm was caused in this case, in the opinion of the stewards, and that no earlier precedent of penalties for this exists – on the one hand; but that it is a breach of the regulation and has potential for serious consequences on the other, the stewards determine to take action in this case and order a fine of 50,000 euros," the stewards said.
Article 2.5.1 of the FIA sporting code says that "inside the Parc Ferme, only the officials assigned may enter. No operation, checking, tuning or repair is allowed unless authorized by the same officials or by the applicable regulations."
Stewards said the footage showed Verstappen's touch is clear.
"(He takes) his gloves off and puts his right hand at the slot-gap of the rear wing of his car. He then moves to (Hamilton's) car 44 and repeats the exercise, touching the rear wing in two places, once on either side of the DRS actuation device, but on the bottom rear side of the wing, in the area of the slot gap and never near the actuator or the end fixation points," the stewards added.
"There is absolutely no movement of any of the wing elements on car 44 when Verstappen touches the back of the wing and the stewards are satisfied, from watching all the videos, his body position and the video of the wing, that there was insignificant force when Verstappen touched the wing."
Saturday's free practice session, which was not very competitive, ended with Alpine driver Fernando Alonso clocking the fastest lap, more than 0.8 ahead of second-placed Verstappen.
The Brazilian GP is the third event of the season with a qualifying sprint race. The two previous sprint races were held at Silverstone and Monza.
Red Bull team principal Christian Horner had said he would be surprised to see his driver punished for checking Hamilton's car.
"Drivers are very inquisitive animals sometimes. We've seen it many, many times," Horner said.