A seventh place in FP1 gave Aston Martin an encouraging start at the Autódromo Hermanos Rodríguez. But a suspected water-pressure issue linked to the Energy Recovery System (ERS) ended Fernando Alonso's Q1 attempt on 31 October, after he briefly went fastest with a 1:18.908 lap. The FIA reported that Race Control brought out the red flags after the car stopped on track.
Alonso was close to the pit lane and told his engineer he could get back to the garage. The team instructed him to stop as soon as possible. His car came to a halt at Turn 14, in the stadium section. Smoke then came from the car, leaving him unable to continue and ending his chance of reaching Q2. Aston Martin described the issue as suspected water pressure loss associated with the ERS; Alonso was classified 18th.
The stoppage followed a promising start to the weekend. Alonso had also shown good pace in FP2 and FP3, although downshift problems had emerged on Saturday. The circuit's altitude is far higher than at the other venues on the Formula 1 calendar. Independent qualifying coverage reported that the stoppage came with about 11 minutes and seven seconds remaining in Q1. Aston Martin teammate Lance Stroll was classified 20th, with a 1:19.072 lap; Lewis Hamilton took pole for Ferrari.
An earlier report had noted Alonso's pace in Mexico, where he finished seventh in FP1 and 12th in FP2. During practice, the Aston Martin also surpassed 350 km/h for the first time that season.
The Q1 failure cut Alonso's race prospects, leaving him 18th in the qualifying order for the 1 November Grand Prix, subject to any later grid changes. After qualifying, Alonso indicated he might not take part in the race, though Aston Martin had not formally confirmed a withdrawal. The stoppage came amid a season marked by reliability concerns for the team and its Honda partnership; coverage also reported plans for a Honda redesign for 2027.
