The 1991 Mexican Grand Prix was a Formula One motor race held at the Autódromo Hermanos Rodríguez, Mexico City, on 16 June 1991. It was the sixth race of the 1991 Formula One World Championship.
The 67-lap race was won by Italian Riccardo Patrese, driving a Williams-Renault, after he started from pole position. Patrese's teammate, Briton Nigel Mansell, finished second, with Brazilian Ayrton Senna third in a McLaren-Honda.
, it was the most recent Formula One race to feature a car powered by a Porsche engine.
Pre-race
In the run-up to the race, Tyrrell had lost talented designer Harvey Postlethwaite to the Mercedes-Benz sportscar team, while Ayrton Senna had been injured in a jet-ski incident. During Friday qualifying, Senna suffered a big accident at the high-speed Peraltada bend, in which his McLaren rolled and landed upside-down, but he emerged unscathed.
Qualifying
Pre-qualifying report
In the Friday morning pre-qualifying session, JJ Lehto was fastest for Scuderia Italia for the third time this season. His Dallara was over half a second faster than the second-placed runner, Fondmetal's Olivier Grouillard. It was the first time this season that Grouillard had pre-qualified and progressed to the main qualifying sessions. Initially, the third fastest driver was Nicola Larini in the Modena Lambo, but he was later excluded when his rear wing was found to be too high. This promoted the two Jordans one position each, with Andrea de Cesaris taking third, a second faster than Bertrand Gachot in fourth.
Missing out in fifth place was Eric van de Poele in the other Lambo, just 0.056 of a second behind Gachot. Over six seconds behind van de Poele was Pedro Chaves in the Coloni, with the team suffering from financial problems. Emanuele Pirro was seventh in the other Dallara, having not posted a representative lap time.
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Championship standings after the race
;Drivers' Championship standings
{|class="wikitable" style="font-size: 95%;"
|-
!
! Pos
! Driver
! Points
|-
|align="left"| 10px
|align="center"| 1
| Ayrton Senna
|align="right"| 44
|-
|align="left"| 10px 2
|align="center"| 2
| Riccardo Patrese
|align="right"| 20
|-
|align="left"| 10px 1
|align="center"| 3
| Nelson Piquet
|align="right"| 16
|-
|align="left"| 10px 3
|align="center"| 4
| Nigel Mansell
|align="right"| 13
|-
|align="left"| 10px 2
|align="center"| 5
| Alain Prost
|align="right"| 11
|-
!colspan="4"|Source:
|}
;Constructors' Championship standings
{|class="wikitable" style="font-size:95%;"
|-
!
! Pos
! Constructor
! Points
|-
|align="left"| 10px
|align="center"| 1
| McLaren-Honda
|align="right"| 54
|-
|align="left"| 10px 1
|align="center"| 2
| Williams-Renault
|align="right"| 33
|-
|align="left"| 10px 1
|align="center"| 3
| Benetton-Ford
|align="right"| 21
|-
|align="left"| 10px
|align="center"| 4
| Ferrari
|align="right"| 16
|-
|align="left"| 10px
|align="center"| 5
| Tyrrell-Honda
|align="right"| 11
|-
!colspan="4"|Source: