Ahead of today's qualifying session the air temperature is 25 degrees C, while the track temperature is 47 degrees. It remains bright and sunny, however race control still warns of a 10% chance of rain.
While there is no doubting Max Verstappen's pace and consistency this weekend, there is still no clear picture of where any challenge might come from.
Not exactly the sentimental type, the Dutchman is unlikely to roll over for his teammate, even if a home win for Perez would make great TV and boost the sport's growing popularity.
Mercedes and McLaren look good back lack consistency, while, courtesy of the Haas pair and Lance Stroll, we have yet to really see what Ferrari can do.
Indeed, if we take it as read that Max and Red Bull have this sewn up, with Sergio taking whatever is left, the real story going into qualifying is who might spring a surprise.
Alex Albon has been strong all weekend, finishing second in both morning sessions, as has Valtteri Bottas, while the AlphaTauri pair looked good earlier, though Tsunoda is destined to start from the back of the grid after taking on a new engine.
Aston Martin's fall from grace appears to be continuing, while Alpine also look out of sorts. And then there's Haas, where the much-anticipated upgrade package doesn't appear to have made a blind bit of difference.
The lights go green first out is Magnussen, who is followed by Gasly, Stroll and Alonso.
Magnussen posts a benchmark 19.730 but it's a low benchmark, despite which Gasly can only manage 19.773.
As the Aston Martin pair begin their first flying laps, the crowd erupts for Perez who is heading down the pitlane.
The Mercedes and McLaren duos head out, all four sporting medium tyres.
Alonso goes quickest with a 19.604 while Stroll goes fourth with a 20.030.
Perez is cheered at every corner and along the straights, the Mexican crossing the line at 18.553 which is greeted with another huge roar.
Tsunoda goes second with an 18.890 but is demoted when Verstappen bangs in an 18.099.
Hamilton goes third (18.677) ahead of Tsunoda, Russell, Piastri and Alonso.
Like Mercedes and McLaren, the Ferrari pair head out on mediums.
With the mediums the drivers are able to get two flyers while the softs are only good for one.
Bottas goes second with an 18.429 but is immediately demoted when Ricciardo posts an 18.341.
"Not sure we're going to get much more out of these," warns Hamilton.
Albon can only manage tenth (19.382) on the softs.
Sainz goes sixth (18.755), but drops to seventh when Leclerc goes third with an 18.401.
Hulkenberg goes eleventh, S Norris finally emerges from the pits, the last driver to do so.
Sargeant has his time deleted for exceeding the limits at Turn 12.
Gasly can only manage 11th and Ocon 14th.
As Norris switches to softs, Sargeant calls for his floor to be checked after running wide. Sainz complains about traffic.
Piastri also switches to softs, the Australian having dropped to 18th on the timesheets.
Replay shows Albon running wide also.
Piastri goes quickest in S2, the Australian crossing the line at 18.241 to go second.
In the pits Russell heads a massive traffic jam with just 2:20 remaining. Hamilton fears he is running out of time.
Verstappen has been noted for impeding at the pit exit.
Norris can only manage 19th as Albon complains that his tyres are "completely gone" having improved to ninth.
Like Verstappen, Russell has been noted for impeding in the pitlane.
As Perez goes sixth, the yellows are waved following an off for Alonso.
Stroll remains 18th while Hulkenberg goes 14th.
The yellow flags and inability to use DRS has caused problems for all manner of drivers.
Russell and Alonso are also to be investigated for incidents in the pitlane.
Quickest is Verstappen, ahead of Piastri, Ricciardo, Leclerc, Bottas, Perez, Hamilton, Sainz, Albon and Alonso.
We lose Ocon, Magnussen, Stroll, Norris and Sargeant.
The stewards have also noted that Russell, Norris and Zhou failed to adhere to the maximum delta time, while Hamilton failed to slow under yellow flags, as did Sargeant. In addition, Sargeant and Tsunoda have been noted for overtaking under yellow flags.
The Bulls are first out for Q2, and again Perez, who heads his teammate, is cheered all the way around the track.
The Mexican crosses the line at 18.124, however Verstappen responds with a 17.625, 0.499s quicker.
"I got told to box for some reason," says Norris. "The pace was good, then I made some mistakes on my lap, and then there was the yellow. I had one opportunity and I didn't take it."
Piastri goes second and countryman Ricciardo third, as Russell goes fifth and Hamilton sixth.
Sainz goes seventh with an 18.382 and his teammate eighth, but both are demoted when an 18.246 puts Bottas 5th.
Albon goes eleventh (19.147), ahead of Hulkenberg, Gasly and Alonso.
"There's no way," complains Albon, mystified by his lack of pace, "there's damage or something."
"For whatever reason the front left is completely gone on this set of tyres," says Leclerc.
With 3:52 remaining, Hulkenberg leads the way as the final assault gets underway. He, along with Albon, Gasly, Alonso and Tsunoda comprise the drop zone, with Zhou, Leclerc and Sainz hovering.
"It's another mess leaving the pitlane again," Albon is warned.
Tsunoda overtakes Ricciardo, suggesting the Japanese might give his teammate a tow seeing as he will be starting form the back of the grid.
Sainz locks-up in Turn 4.
Hulkenberg improves to tenth, but is it enough?
Alonso can only manage 12th, while Sainz fails to improve.
Russell goes quickest in S2 as Leclerc goes fourth and Ricciardo second.
Russell goes second, Bottas sixth and Hamilton quickest with a 17.571.
Albon improves to ninth with am 18.302, thereby demoting Zhou to eleventh.
Quickest is Hamilton, ahead of Verstappen, Russell, Ricciardo, Piastri, Leclerc, Bottas, Perez, Albon and Sainz.
We lose Zhou, Gasly, Alonso, Albon and Tsunoda... as Albon's time is deleted for exceeding track limits at Turn 2, thereby promoting Zhou back to tenth.
Check out our Saturday gallery from Mexico City here.
sign in