It may as well have been Sunday. Jordan Spieth celebrated – putter aloft, adoring crowd roaring – having converted from the fringe of the 18th green for a birdie. Hard facts show tournaments are not won in the third round, but even Spieth seemed to appreciate the significance of this moment in time. It will be a shock if the 23-year-old does not claim the Open and the third part of a career grand slam.

Spieth and Matt Kuchar will take to the course at the back of affairs on Sunday , the contrasting aspirations therein testimony to how the sport can span the ages. Kuchar played in the 1998 Open here; Spieth was five at the time.

Kuchar remains in pursuit of maiden major success. Spieth’s three-stroke advantage – he sits at 11 under after a second 65 of the week – renders him the overwhelming favourite, as does the earlier collection of major titles. Still, there is a fascinating and potentially negative back-story for Spieth. He has not won any of the four marquee events since the dramatic and disastrous capitulation that cost him the 2016 Masters from a supposedly unassailable position.

To his credit, Spieth refuses to hide from or mask that recurring Augusta nightmare. He even said it will form part of his psychological make-up in advance of round four.

“I’m in a position where it can be very advantageous, just everything I’ve gone through, the good, the bad, and everything in the middle,” Spieth said. “I understand that leads can be squandered quickly and I also understand how you can keep on rolling on one. So that was a humbling experience that I thought at the time could serve me well going forward.

“You’re learning and it all goes into the mental process. It will be a day that will be emotionally draining and difficult to stay very neutral in the head, but that’s probably the most important thing for me to do. We have an opportunity to have a really special day. I’m excited about it.”

Kuchar’s 66, a terrific effort in its own right, could not stem the flow. “I’m going out to play Royal Birkdale on Sunday, not to play Jordan Spieth,” Kuchar said. Which is just as well.

Even when the 39-year-old tied the lead with a birdie on 15, Spieth jabbed back with a four of his own. Kuchar was to double bogey the 16th with even a penultimate hole recovery deemed rather irrelevant as Spieth produced magic in front of the clubhouse. Any prospect of Kuchar outscoring Spieth by four on Sunday, or another contender blasting past both from the pack, is difficult to envisage.

“It’s a different feeling and one that’s harder to sleep with than the other way around because you feel like you’ve got to almost change the way you do things,” said Spieth of holding a 54-hole lead. “You almost see the finish line. You control your own destiny and sometimes that can be a big thing on your mind versus: ‘I need help and I’ll just go out there and try to play well. If I get help, great, if I don’t, I don’t.’”

Brooks Koepka’s dropped shot at the last meant he slipped back to five under and the position of needing snookers. Hideki Matsuyama is a shot worse off with Dustin Johnson – a suddenly reinvigorated world No1 – Henrik Stenson and Rafa Cabrera-Bello among those at minus three.

Rory McIlroy had threatened to gatecrash the party before a disastrous double bogey at the 10th, the kind of heavy scorecard error that has affected his 2017 results. McIlroy has Ross Fisher, Richie Ramsay and Ian Poulter for company at minus two and while he ultimately cut a frustrated Saturday figure, there has been plenty for McIlroy to be upbeat about since Thursday.

“It’s hard to think big picture now. I’m just off the course and I’m a little disappointed,” he said. “This week has been a step in the right direction, there’s no doubt about it. I need to pick myself up, play a good round tomorrow, hope for some bad weather and hope for some guys to struggle. And we’ll see what happens.

“I definitely feel like today was an opportunity lost to get right in the mix.”

The most remarkable leaderboard story of them all is Austin Connelly, a 20-year-old dual national of the United States and Canada. His facial complexion is so boyish he would struggle to purchase cigarettes but there is nothing inexperienced about his game.

Connelly, who has created only minor ripples on the European Tour this season, converted from 20ft at the last for a 66 and five under aggregate. He sits on the same score as Koepka, ahead of major champions and players ranked considerably higher than Connelly’s placing of 524th. It further emphasises what feels like Spieth’s grip on this Open that he shares a coach with Connelly. “He’s got a great head,” said Spieth of the youngster. “He’s got a killer instinct. He’s a guy that’s not afraid of the moment, as you can tell.”

The day had opened with Branden Grace making history, catapulting himself to four under for the tournament and a share of fifth in the process, with his 62. He, and others, now live far more in hope than expectation.