They were one man down. Trevor Seaman, a tough wrench who'd served in the armed forces before joining battle at Team Lotus, felt woozy even in Canada.
Now, after the drive down through the Finger Lakes district to Watkins Glen, he was out of it. Confined by the local doctor to bed and to complete rest, Trevor could only stare at the ceiling of the sparse motel room over the days that followed, trying not to think about the workload the other five boys would face...
Munching a bacon sandwich in Watkins Glen's Kendall Tech Centre, staring at three Lotus 49Bs - the race cars for Graham Hill and Jackie Oliver, plus a spare - Bob Dance, Gold Leaf Team Lotus chief mechanic, wondered if he could take much more.
They'd lost Jim Clark earlier that year; they were fighting hard to win Graham the championship; everyone was scared of the high wings that had become the F1 norm; and everything, as ever, was on the limit.
Ahead of him: three engine changes plus new upper and lower engine mountings, new driveshafts on all three cars... and the usual stuff in between.
The driveshafts alone were a massive job, and he was probably going to have to do those himself, leaving Bob (Sparshott), Eddie (Dennis) and Dale (Porteous) to focus on the other work...
It was three days before practice - and well after the engine swaps had been completed - that Colin Chapman flew in from England with the news that would forever change the racing world: Mario Andretti would be racing a third 49B at the Glen. Oh yes. And there would be a change of plan regarding the engines: Mario would race with the team's second-best Cosworth DFV.
Graham, as the championship contender, would have the single fresh engine but Oliver's Cosworth would have to go to Mario.
Stunned by the last-minute increase in workload, but delighted to be seeing Mario again, Bob sat the boys down to prepare for another all-nighter. And still there were the CV driveshafts to finish... cleaning, measuring, re-fitting...
For Mario, this was retribution for memories of a Monza that still rankled. He'd tested a 49B at the Autodromo in the week before the race and been quickest overall - quicker than Hill and quicker than the Ferraris of Chris Amon and Derek Bell.
And, although he'd been committed to the Hoosier 100 USAC dirt race at Indiana State Fairgrounds the weekend of the Italian GP, he had managed everything to perfection. The Monza organisers had no problem with him flying back to the US after first practice - and the time change had worked in his favour. The plan was to be back at Monza by Sunday, ready to start his first GP.
It had all worked perfectly. He'd qualified top ten on the first day at Monza and he'd slept soundly on the flight back to Chicago. By the time he flew into Indy he was ready to race.
He qualified on the pole, relishing the feel of the big, front-engined Offy sprinter after the lightness and agility of the 49B - and he finished second in a frantic, dirt-spraying final to AJ Foyt. Then came the news from Colin Chapman: the Italian GP organisers, led by clerk of the course Giuseppe Bacciagaluppi, were now refusing to allow Mario to start at Monza.
Probably Ferrari were behind it. Probably he had been too quick in testing....
Lotus didn't need the complication of having to run a third car at Watkins Glen, thousands of miles from home, and a man down after a chassis-breaking Canadian GP... but then nothing was ever easy at Lotus.
The upside, for everyone, was that Mario was in some ways another Jimmy: he was a super-quick, class act. They knew that from Monza - and they knew that Mario could drive anything, anywhere, like Jimmy. He'd won the 1967 Daytona 500 NASCAR classic. He'd been Rookie of the Year at Indy in 1965, the year Jimmy had won.
No matter that he'd never driven at Watkins Glen before. Mario would handle it.
Practice began in the rain. Graham shrugged off his dark blue Speedwell/Hill rally jacket and tried a new "closed-face" Bell visor.
Mario, in red Firestone jacket, remained calm and relaxed. Chris Economaki and the American press followed him at polite distance.
They watched as he tip-toed the high-wing 49B through the sweepers, between the light blue Armco barriers, squeezing on the power and jinking the rear as rooster tails of spray defined his progress.
Although the rain stopped on Saturday, clouds still gathered at Team Lotus.
Early in the morning, Jackie Oliver walked away from the second huge accident of his season. A rear wing had failed in France; at the Glen, a rear wheel broke, tearing his 49B apart against the guardrail. The Lotus compound, inside the Tech Centre, became a scene of horrified chaos:
Colin Chapman (black-eyed): "Why was Jackie running the old Melmags? We flew in the new wheels specially last night!"
Bob Dance (red-eyed): "Why didn't anyone tell us about it? We were flat out! They obviously just got put in a corner..."
Everyone - Chapman, chief designer Maurice Phillippe, Graham, Mario - then set to work on the wheels, bolting together the new ones, rushing them over to Firestone and in between times fetching the tea.
Graham and Mario kept the ship afloat, firing wisecracks and one-liners, bringing a smile even to the face of Colin Chapman.
Until, finally, they were ready. A dry track, a golden afternoon. Autumn in New York.
Graham ran new Firestones; Mario began with used ones. They thought he wanted to put in more laps on a circuit still new to him. They thought he would later switch to fresh rubber.
Mario had another plan. In tyre testing that year, in the USAC Hawk on road courses, he'd unlocked the power of the slick. You could run the tyres until the tread began to go away and then - only for a lap or two - there'd be a sweet spot around which the grip would be immense.
He never mentioned this to Colin or to Maurice - and he didn't talk about it with other drivers, or even with Firestone. He knew about it, though.
He could feel it just as surely as he could feel the downforce of a high rear wing. And he was going to apply it at the Glen.
He tied up his face mask. He strapped on his Bell Magnum. He pulled on his skin-tight leather gloves, spitting on the palms. He climbed into the 49B before settling back as Eddie tightened the belts. And then he was off.
He put in the laps. One. Two. Three. Four. Jackie Stewart had pole in the Tyrrell Matra... but now Mario was closing on the powerful Honda of John Surtees.
Maybe he'd get a tow down the back straight. The Firestones were by now well-worn - across the line... 1m4.2s!
Mario Andretti had taken pole for his first F1 race on a circuit he'd never seen before. It was October 5, 1968. It was fifty years ago.