The real test comes Sunday, when he'll have to find a way to come from behind and actually win the Open - something he didn't do even in his prime.
Spieth began the day one one-over after dropping four shots in his last four holes on Thursday, but started heading up the leaderboard with a stroke of magic on the third - chipping in from off the green for a birdie.
The defending champion never looked back after making a "dream start" en route to a six-under-par 65 for a three-way tie with Xander Schauffele and Kevin Kisner at Carnoustie. Out here with the firm fairways, you've got to really pick and choose what you're going to do. "I've still got a lot of work to do this week, and I'm not going to take anything for granted", Johnson, who has two other top 10 British Open finishes, said. "It's a bonus to get on the green and obviously for the putt to kind of curl in".
The three-time major victor arrived at the Angus links on Saturday afternoon sporting a rather severe-looking short back and sides but a superb 65 catapulted him to nine under and set up a long-dreamed-about final-day tussle with a resurgent Tiger Woods.
A five-under-par third round at The British Open has Tiger Woods in contention at a major for the first time in years.
He didn't have the best score. "But who knows? They're damn good players".
Rose missed that putt but tapped in for a birdie, hit a fine chip stiff from pin high to the raised 16th green to save par and then produced his wonderful finale, although he feels that the 64 which matches the 2007 rounds by Steve Stricker and Richard Green will only show the rest of the field what is available. Will this be his breakthrough? If he matches his Friday round of 66, he might be able to win this thing.
However, that 71 could actually see him move backwards or at best stay where he was last night at T-52.
Fellow early starter McIlroy, by contrast, was extremely pleased after he mixed four birdies with two bogeys.
Carnoustie, often the most hard course on the Open rota, was there for the taking.
Par figures were nearly at a premium for McIlroy as he littered his round with four bogeys and five birdies.
Woods, who is 42 years old these days, has not won a major since 2008. American Kevin Chappell made the sole birdie and there were 25 bogeys and eight double bogeys or worse. Just go out there and give it your all, try 100% rather than hold back and maybe not give myself the opportunity to do well.
Perhaps none of the leading men will go full Jean Van de Velde, the star-crossed Frenchman who could still be standing in that burn if not for a rising tide back at the 1999 championship, but if the 499 yards of dusty turf is an uninvited guest, it's a guest nonetheless. "Between -5 and -9 there's only a handful of guys". But on the very next hole, he gave a shot with a bogey on 16th.