The 23-year-old will take a three-shot lead into the final of The Open Championship after a piecing together what was seemingly a methodical bogey-free five under 65 to reach 11 under. He leads fellow American Matt Kuchar by three strokes.

A victory on Sunday would make Spieth just the second player after Jack Nicklaus to have won three of the game’s four major championships before the age of 24. By adding the third leg of the Grand Slam, the World No.3 could then break Tiger Woods’ record as the youngest player to complete a career Grand Slam at the US PGA Championship at Quail Hollow next month.

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With so much history and the Claret Jug beckoning, the young Texan is keen not to get ahead himself, with memories of his 2016 Masters meltdown – when he squandered a five-shot lead on the back nine on Sunday to lose – still vivid.

“It would be incredible (to win),” Spieth said. “But I’ve had a five-shot lead in a major and squandered it before. I’ve had the high and the humbling so I will keep my head down and not get ahead of myself.

“I think 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. I understand that leads can be squandered quickly, and I also understand how you can keep on rolling on one.

RIGHT: Jordan Spieth rolls in his fifth and final birdie of the day on the 18th hole. PHOTO: Andrew Redington/Getty Images.

“It (the 2016 Masters) was a humbling experience that I thought at the time could serve me well going forward. And if I don't win tomorrow, it has nothing to do with that. It has to do with it was someone else's day, and I didn't play as well as I should have. And if I win tomorrow it has nothing to do with that, either.

“You're learning and it all goes into the mental process. And as I go in for the next whatever, 18, 20 hours, it's about being very positive and really staying very focused on a game plan for tomorrow. Relax … smile more, Michael is doing a great job keeping us loose. It's been pretty easy and it's not going to get any easier.

“Tomorrow 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.”

Of concern to Kuchar, who at 39 is still looking for his first major victory, and the rest of Spieth’s pursuers is that he has converted all five of his last 36-hole leads into victories.

Matt Kuchar drops to his knees after his birdie attempt on the 18th hole slides by. PHOTO: Andrew Redington/Getty Images.

Spieth began the third round with a two-shot buffer on his nearest rivals and look set to blow the field away with three front nine birdies. But playing partner Kuchar kept in touch with three birdies of his own.

Kuchar and Spieth both turned in 31 strokes and for about two minutes on the 15th hole Kuchar grabbed a share of the lead having converted his second birdie in as many holes. But Spieth replied with a birdie of his own to break clear again.

THIRD ROUND LEADERBOARD   |   FINAL ROUND TEE TIMES

Kuchar double bogied the par-4 16th hole, which saw Spieth’s lead stretch to three for the first time. A birdie on the 17th saw Kuchar narrow the margin to two again and he looked set to roll in another birdie at the last, only to miss from six feet after Spieth brought the huge crowd to its feet by holing his own birdie from twice the distance.

Kuchar will play alongside Spieth in the final round and says he needs to avoid playing match play with his Ryder Cup team-mate.

“I’ll be playing with him but not focused on him,” Kuchar said.

Ryder Cup team-mates Kuchar and Spieth will play alongside each other again in the final round. PHOTO: Andrew Redington/Getty Images.

“My goal is to go out and play Royal Birkdale. I’ll know exactly where we stand but I don’t know how much that ever helps you.

“You just have to go out and hit the best shot for the situation. I’ve been in some good form. The formula has produced a lot of good golf and I hope it continues to produce some good golf tomorrow.”

US Open Champion Brooks Koepka (68) and 20-year-old Canadian-born Texan Austin Connolly (66) are six shots adrift of Spieth at five under and will play in the penultimate group of the final round.

South African Branden Grace, who carded his history making eight under 62 in the third round, will play alongside Japan’s Hideki Matsuyama in the third last pairing. Both players are four under after 54 holes.