Carlos Sainz brought the Ferrari cars home in fifth place, finishing almost a minute behind the race winner Max Verstappen and nine seconds behind fourth place George Russell despite the Mercedes driver making a late extra pit stop to claim the bonus point for fastest lap.
Leclerc was a further 10 seconds adrift in sixth to cap a difficult weekend for Ferrari, who have spent the first half of the season battling Red Bull for top spot.
“It was incredibly difficult, we were very slow, so yes, we need to look at it,” Leclerc said after the race.
“We were in the middle of nowhere. With Carlos we were much slower compared to Mercedes and Red Bull, [but] much faster than midfield. So we were on our own, just a very lonely race.
“Honestly, we couldn’t have done more today.”
Charles Leclerc, Ferrari
Photo: Zak Mauger / Images of motor sports
The race saw Mercedes level with Ferrari on 40 points for second place in the Constructors’ Championship, leaving the Italian team over their shoulder in the final two races of the season.
But Leclerc doubted Ferrari would struggle in Brazil or Abu Dhabi with the same difficulties as in Mexico, suggesting it was an exception to the season.
“I hope we don’t do worse because I don’t expect a worse race than this one,” said Leclerc.
“It’s probably one of the worst races along with Spa. I honestly think it’s a one-off.
“But in the future, we need to understand what we can do better in these conditions to make us better.”
While Ferrari struggled with tire degradation compared to Red Bull in recent races, the team found themselves unable to run the power unit at full power due to altitude difficulties in Mexico City and subsequent engine problems.
Ferrari F1 boss Mattia Binotto confirmed the team “didn’t have the chance to continue with maximum power” in Mexico, but felt there was more to explain its struggles as the car “didn’t satisfy the track” all weekend.
“In terms of the power unit, we weren’t at our best over the weekend, but I don’t think that’s the main thing,” he explained.
“That’s part of the equation, but there’s more. There’s definitely more to it than that, and that’s something we need to look at, and there’s no definitive answer right now.
“The trip was not very good. The balance was not great. I’m pretty sure if I listen to the drivers later in the debriefing, they’ll tell me that the car didn’t turn, and the reason why I think that’s something to look for, and we don’t have a clear explanation right now.”
Additional reporting by Philip Clearen