And beating a resurgent Woods to achieve it is something the Texan is relishing.
Everywhere you looked there were fireworks.
It's called Moving Day for a reason.
"Today was a day that I had a great opportunity", Woods said.
Also playing himself out of contention on a day featuring plenty of birdies is Jason Day, who also made 6 at No. 12 and is 1 over after 15 holes. So big credit to my wife that watches me all the time. Scotland's unusually dry summer finally got a reprieve.
When the cards settled, Spieth took up his familiar position at the head of the Open, 12 months after that remarkable victory - sparked by an unlikely escape via the practice ground - at Royal Birkdale.
The 24-year-old Californian burst on to the scene by winning twice in 2017, at the Greenbrier Classic in West Virginia and at the lucrative, season-ending Tour Championship in Atlanta.
Another American Kevin Chappell is two shots off the lead with Italy's Francesco Molinari on six under and Woods another stroke back alongside Rory McIlroy, Tommy Fleetwood, Webb Simpson, Alex Noren, Matt Kuchar and Zach Johnson.
Fleetingly, Woods grabbed a share of the lead with a birdie at the 15th, but dropped back again at 16. So to get to shoot 6-under yesterday was massive. He'd dodged a bullet and took advantage by laying up in front of the Barry Burn and then firing a dart to a few feet to save his par.
The former world number one was visibly irritated by the interruption after enjoying a surging return to what looked like his best form as he piled the pressure on his rivals early on Sunday.
"I was trying to play for the grass to wrap the shaft around there and hit it left, and I was just trying to hold the face open as much as I possibly could". I had to stay within reach.
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The sun was peeking out of the clouds and Woods was walking up the first fairway when one spectator shouted, "Go on Tiger, we got your back".
Speaking to reporters after his round, he said: "We're not there yet. I felt like I was ready for it". He was delighted to have been asked. It's the closest he's been to the lead in a major since five years ago at Muirfield.
Scandal in his private life broke later that year, tipping his whole compass off-axis.
The 35-year-old now has three wins and two runner-up finishes in his last seven tournaments.
He quickly set aside his anger and produced a sublime approach shot onto the green - Molinari congratulating him as the passed - taking the applause of the crowd with a wave of his cap.
So given the backstory, the thrill of the competition lit Woods up like a beacon Saturday.
"I'm right there", he said.
Spieth also said that the presence of Tiger Woods on the leaderboard is a sign of things to come rather than a flash in the pan. Once they saw guys going low, it was nice to get a following out there.
U.S. golfer Tiger Woods watches his iron shot from the 5th tee during the third round of the British Open.
"Judging by the conditions and what's going to be going on, I would imagine it's going to be more of a grind all day", said Kisner, who has been sharing a house with Spieth and several other American stars in Scotland this week.