Harvey, who qualified only 24th yet was fastest of the Rahal Letterman Lanigan-Hondas in a strangely poor event for the team so far, was on his 26th lap of the 1.5-mile track in final practice when his car understeered in the middle of Turn 2.
Harvey downchanged, his car started oversteering, and its right-rear wheel appeared barely to kiss the wall, but it was enough to unsettle the car and wrench it out of the Briton's control.
