Marc Marquez has been stripped of his sixth-straight Austin MotoGP pole position after he was deemed to have impeded Maverick Vinales at Turn 15 in the closing stages of qualifying.
Marquez was winding up for his second run following an earlier crash at Turn 13 when Vinales, who was on a lap that threatened to knock the Honda rider off top spot, was held up by him and forced to abandon the lap.
The Honda rider went onto claim pole with a 2:03.658s, but the incident was soon placed under investigation.
Race Direction deemed Marquez was riding unnecessarily on the racing line and disturbed Vinales' lap, and has been handed a three-place grid drop for Sunday's Americas Grand Prix.
Marquez's penalty gifts Vinales his first pole since Aragon last year, with Suzuki's Andrea Iannone and Tech3 rider Johann Zarco moving up to second and third respectively.
The Honda rider will now start from fourth, ahead of bitter rival Valentino Rossi and Ducati's Jorge Lorenzo.
This penalty means Marquez will start off of pole position for the first time at the Circuit of the Americas.