A raft of grid penalties have mixed up the grid for F1's Mexican GP

McLaren drivers Fernando Alonso and Stoffel Vandoorne came into the weekend facing hefty penalties for engine changes, with Honda saying it is "very ashamed" by the need to boost their pool of available components to make it to the end of the season without incurring more.

Vandoorne has a 35-place penalty and Alonso a 20-place penalty, but they will start ahead of Toro Rosso's Pierre Gasly, whose 15-place penalty has grown to 20 with the addition of a new Renault turbocharger ahead of the race.

The French rookie failed to participate in Saturday's qualifying session and has been handed special dispensation by the stewards to start the race.

As per F1's sporting regulations, Gasly will start last regardless of the fact Vandoorne has a heftier grid penalty that would ordinarily have dropped the McLaren behind the Toro Rosso.

Team-mate Brendon Hartley drops from 13th to 17th on the grid after breaking down in qualifying and requiring a new engine, turbo and MGU-H ahead of the race, while Red Bull's Daniel Ricciardo has tactically chosen to take the same set of new engine components on his car after a disappointing qualifying session yesterday.

He will start 16th after receiving a 20-place penalty.