The reliability of the Lotus cars had been another issue entirely, however, and, when the series returned to North America for the final two races, the only remaining contenders for the Driver's Championship were Brabham teammates Sir Jack (the defending Champion) and Denny Hulme.

Friday practice began under a dark, misty cloud and, as the weather slowly improved, the Lotus cars again posted the fastest times with Clark ahead of Hill.

Late in the session, Clark posted a 1:06.07, breaking the 125 mph average speed barrier, and seemingly securing the pole.

Dan Gurney, who had become the first American to win a Grand Prix in a car of his own design at Belgium, was third in the Eagle-Weslake, and Chris Amon was fourth in the only Ferrari present.

The previous evening, Walter Hayes, public affairs director of Ford of Dagenham, who had contributed £75,000 toward the development of the Cosworth-Ford V8, demonstrated his confidence in a good showing by the two Lotus-Ford drivers when he proposed that they should flip a coin to choose the winner, in case both cars were in contention at the end of the race!

At the start, the Lotus teammates jumped into the lead, and at the end of the first lap, Hill led Clark, Gurney, Brabham, Amon, Hulme and Bruce McLaren.

The Scot craned his neck around to assess the damage, and began nursing the car toward the finish, taking particular care on left-handers!