Vettel stuns Hamilton with Mexico pole - but Verstappen to face stewards again
If Lewis Hamilton is to take the 2017 World Championship title on Sunday, he won't do it from pole position after Sebastian Vettel put in a stunning lap to take top spot on the grid.
Hamilton's time was only good enough for third - but he could yet be promoted to the front row if Max Verstappen, who set the second fastest time, is penalised by the stewards for the second week in succession.
Last time out in Austin the Red Bull youngster had his podium snatched away from him at the end of the race when the stewards decided he had left the track to overtake Kimi Raikkonen on the last lap.
He was furious about the call and now he could be facing yet more trouble from the stewards after a stellar lap at the Autódromo Hermanos Rodríguez on Saturday.
His time looked quick enough for pole for some time, and though it was eventually bettered by Vettel's time, before that the stewards announced they would be investigating a possible block by Verstappen on Mercedes driver Valtteri Bottas.
Bottas said his lap was ruined but Verstappen immediately said there was nothing to investigate.
"There is no incident," he told Sky's Rachel Brookes.
"It's his own problem if he outbrakes himself at the next corner. I was on the inside and didn't hold him up.
"I moved to the inside and was past the point where you go to the right. I don't see an incident."
The Dutch racer has been told to report to the stewards at 9pm GMT so a decision should follow some time after that.
If he is found guilty of blocking, he could see his front row starting position taken away. Williams driver Lance Stroll and Kevin Magnussen of Haas were both given three-place grid penalties for blocking Romain Grosjean and Sergio Perez respectively in Austin last time out.
The stewards eventually decided not to penalise Verstappen for the move.
A statement read: "The stewards examined multiple angles of video evidence and radio calls to car 33, and heard from Max Verstappen, the driver of car 33, Valtteri Bottas, the driver of car 77 and the team representatives.
"The driver of car 33 was clearly aware from the team radio and using his mirrors that car 77 was approaching on a hot lap.
"He moved from the racing line on the exit of turn 12 to avoid impeding car 77.
"The driver of car 33 did move slowly from the racing line which could have affected car 77, but the stewards do not consider this as impeding."
Elsewhere, Lewis Hamilton only needs to finish fifth tomorrow to seal his fourth drivers' title.
He said his lap was the best he could get out of the Mercedes today.
"I gave it everything I could. It just wasn't the cleanest of sessions and they were quicker," he told Sky F1.
"The car balance was fine. We needed more.
"At the moment there is no risk to take. If I get a good start and am in a good position I will go for it. At the moment that's an unknown."