While Justin Thomas was the headline act at Erin Hills on Saturday courtesy of a sensational nine-under 63, the lowest score to par in the tournament's history, it was Harman who ended round three at the top of the leaderboard.
Harman, who had begun the day in a four-way tie for the lead, carded a five-under-par 67 which included six birdies and one bogey. Fleetwood isn't a household name in the USA, but he's a rising star on the European Tour. "So we're breaking down all kinds of barriers". "I'm proud of the way I hung in there today".
Harman, who won the US PGA Tour's Wells Fargo event in May, climbed to 12 under and will take a one-shot lead into Sunday's final round over world No.13 Thomas, Brooks Koepka and England's Tommy Fleetwood (both 68) sharing second place. 15 and 17 before he hit a 3-wood on his approach shot on the par-5 18th hole to set up a short eagle putt that allowed him to get to 11-under.
The wind at Erin Hills is finally expected to pick up for Sunday's final round, which could put a halt to all the record-setting scoring that's made the U.S. Open leaderboard look more like one at a regular PGA Tour stop.
It was the third birdie Thomas had registered in the opening five holes and allowed him to return to three-under for the round following a bogey on the fourth. Then I 3-putted the 7th because of a spike mark in my line on a 1.5 foot second putt.
"I hoped that this moment would come as soon as possible". I felt like I made a couple of good putts there coming in on 8 and 9, just didn't happen to go in.
Fowler is within two strokes of the lead at minus-10.
"Someone has a very good chance of ending up with their first major [Sunday]", Fowler said. "To have a chance tomorrow is just going to be great", said Thomas. "I'd love to have another one of those", said Thomas, who posted at 11-under 205. It's not going to be an easy day, for sure. I've been there a handful of times and had some good finishes. This is why I play - to get myself into this sort of position.
Rickie Fowler has a shot at winning his first major if he can stay out of trouble.
Around 70 minutes earlier, compatriot Patrick Reed had faced a similar length putt to Thomas on the 18th to shoot eight under but missed his birdie attempt and had to settle for a 65.
The player hit eight birdies during the third round, but a bogey on No. 5 stunned the start of his day. Erin Hills is the longest course in Open history, but it has 50-yard-wide fairways that have played even wider after rainstorms.
But birdies will be harder to come by on Sunday with winds gusting from 25-30 miles per hour (40-48 kph), bending flag sticks and moving balls over hardening greens.
Oosthuizen, whose sole major title to date came at St Andrews in 2010, birdied the first, fourth, seventh and eighth to move to four under par, while 2015 victor Spieth had covered his first 11 holes in level par. Since Zach Johnson added the Open to his Masters in 2015, Jason Day, Danny Willett, Dustin Johnson, Henrik Stenson, Jimmy Walker and Sergio Garcia have broken their duck.