As carefree as things appeared on Saturday when 13 players, including Spieth, posted rounds of 67 or lower, as tame as Carnoustie, which stands alone as The Open's undisputed bully, has been through 54 holes there was a foreboding tension among the rank and file as they readied for a final trip around Royal Brown & Bouncy.
Kevin Chappell, who spent most of his round watching Spieth put on a show, birdied the 18th for a 67 and was two shots behind. And that was only the beginning of a sequence in which Tiger Woods vaulted into a tie for the lead, Spieth reclaimed it, Rory McIlroy approached it and roars erupted across Carnoustie.
"I'm committed to making sure, even if I don't play my best golf and don't shoot the scores I want, I'm going to go down swinging and I'm going to go down giving it my best". He shot 72 and was in the group four behind.
"I'm right there. I've got a chance at this, which is great". 4, 9 (with a 30-foot putt), 10, 11 (with a stress-free two-putt from 95 feet) and 14 (with another stress-free two-putt). "So I think it's going to be a true test, and we'll get to see really who's hitting it the best and playing the best tomorrow", said Kisner, who added a 68 to his total on Day 3. And Woods's playing partner sensed an aura around the 14-time major champion. Especially if we get the weather that has been forecast.
Tiger Woods during British Open golf third round action in Carnoustie July 21, 2018.
Woods' presence, too, nearly overshadowed the curiosity surrounding the fact Spieth got himself a morning haircut from a local barber whom he sought out searching on Yelp.
Spieth had got his round going with an eagle at the par-4 first hole which signalled his intent, and a birdie on the 4th to 6 under.
Spieth has his work cut out though, with the leaderboard so closely packed that at least 20 players will start Sunday believing they can win the Claret Jug.
He holds the course record at Carnoustie with a 63 at the Dunhill Championship a year ago and also shot 63 on the final day of the US Open last month to finish second behind Brooks Koepka. Joining them was Tommy Fleetwood, who dropped three shots in two holes on the back nine on his way to a 71.
Of the five players separated by three shots, only Spieth has experience winning a major.
There would be a sense of symmetry to the achievement if Spieth does win on Scotland's North Sea coast - Harrington's double came at Carnoustie in 2007 and then Birkdale in 2008.
Greller told him no. Play short and it's a wedge to a front pin, easy birdie chance.
Meanwhile, Fleetwood is the most likely to become the first English victor of the Claret Jug since Nick Faldo in 1992.
"I hit a lot of good shots".