Jordan Spieth has no idea what to expect Sunday.


Because he has created a fascinating unpredictable aura about himself, something he’s the first to acknowledge. It’s a wonderfully intriguing wild ride between spurts of dominance and bouts of vulnerability.

Spieth never has been more vulnerable than when he lost that five-shot lead with nine holes to play at the 2016 Masters. Yet, he had closed out his previous five 54-hole leads before that Augusta implosion, and he has converted his past four since his harrowing tussle with Rae’s Creek.

Then there was last month at Royal Birkdale, where he was about to blow the British Open … and then he didn’t, somehow steeling his nerves from the practice range during his final round and winning in a mini-runaway on the final five holes.

This brings us to Sunday at Glen Oaks Club in Old Westbury, where the final round of the Northern Trust will play out with Spieth holding a three-shot lead over Dustin Johnson.

“I’d expect anything,’’ Spieth said when asked what his nearest competitors should expect with him holding the lead. “I’ve kind of shown that anything can happen — unfortunately and fortunately. I imagine it’s not like guys that were chasing Tiger [Woods] where you almost felt hopeless.’’

It’s that kind of unfiltered view into his soul that makes Spieth so endearing. He knows he’s good, but is humble enough not to flaunt it. He, too, is well aware of his vulnerability.

You could not have asked for a better, more compelling final round to unfold Sunday at Glen Oaks.

Anyone with the nerve to ask for more than Spieth leading the tournament with Johnson in hot pursuit and Jon Rahm, Patrick Reed, Paul Casey and Matt Kuchar, the British Open runner-up, also in the chase, is just plain greedy.

Spieth, still glowing from his British Open victory, had the look and the walk all day Saturday, shooting a dazzling 6-under 64 and vaulting into a three-shot lead over Johnson. Spieth, who’s 11-under in his past two rounds, is 12-under. Johnson is 9-under.

Reed, who shot 66 Saturday, Rahm (67), Kuchar (68) and Casey (66) are all 7-under. Local favorite and former St. John’s star Keegan Bradley played himself into the cusp of contention at 6-under with a third-round 66.

It all makes for a potential wild Sunday shootout with the confident Spieth in “come-and-get-me’’ mode.

“I like coming from behind,’’ Johnson said. “Obviously, Jordan’s playing really well, so he’s going to be tough to beat. Maybe some of his putting will rub off on me and I’ll start holing them. I think it’s going to be a fun day.’’

This is the 15th time Spieth has had at least a share of the 54-hole lead. In cold-blooded-killer, Woods style, he has converted nine of his past 10 into victories, the last being at Birkdale for the Claret Jug.

“My putter started to heat up in the second half of [Friday’s] round and I kind of created my own confidence, and that has led into the last 27 holes and some of the golf I’ve ever played,’’ Spieth said. “Anything can happen [Sunday], but if we stay focused on the goal and swing the club well, we’ll be fine.’’

Spieth’s pursuers already were speaking with reverence on Saturday about his ability to close.

“You need to have a really good round, because that guy can seriously close it out,’’ Rahm said. “He’s not going to give it to you. Spieth is not known for being one to stumble. Last time, he actually made a little bit of a mistake and ended up with a finish for the ages at The Open.’’

Casey, a veteran who had his hopes dashed a time or two by Woods back in the days of Woods’ dominance, was asked if he sees any similarities in Spieth.

“Putting-wise, yes,’’ Casey said. “Tiger was just pure dominance. The all-around game was just mind-blowing. [But] you didn’t see Tiger hitting it off the practice ground at an Open Championship and making errors and then amazing comebacks [like Spieth did from the driving range at Birkdale after his tee shot on 13 went 100-yards wayward right]. You just saw dominance. He took off and you never saw him again.

“Jordan’s got something very special. What he did at the Open Championship was brilliant, absolutely brilliant, after the start. He’s got something very, very special. Ask me again in another decade to define it and maybe I’ll have a better grasp of it.’’