Lewis Hamilton has placed the blame for his miserable São Paulo Grand Prix on the Mercedes floor.
The seven-time F1 World Champion started fifth and was third by the time red flags were thrown for a first-lap incident that took a number of cars out of the race.
But despite challenging McLaren's Lando Norris into Turn 1 at the restart, a lack of pace in the W14 left Hamilton struggling to fight his rivals.
After Red Bull driver Sergio Perez and Aston Martin duo Fernando Alonso and Lance Stroll jumped ahead, Ferrari's Carlos Sainz and Alpine's Pierre Gasly also made moves to leave Hamilton down in eighth, losing vital ground to Mexican Perez in the race for second in the Drivers' standings.
"My guess is that the floor is not working," Hamilton told media including RacingNews365.com.
"The floor is not sucking it down. So that pushed us to go to a higher wing, and then we're just massively draggy on the straights.
"And we're losing so much time on the straights, there's nothing I can do about it, and then we're just sliding through the corners. So we have to look into why that is the case on this rough circuit."
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'I knew we'd have a difficult day'
Mercedes' downfall mirrored the issues that plagued the team's Sprint fortunes on Saturday, despite a change in temperatures overnight.
Asked whether he had hoped for a more positive outcome, Hamilton replied: "I knew that we'd have a difficult day,
"Nothing changed in the car [overnight]. So I knew it'd be a tough one.
" I just ate through the tyres [in the Sprint] with an unexpected lack of pace and then I think I drove better [in the Grand Prix] in terms of making my stints, but we were just slow."