But even with his historic round, Thomas, 11-under for the weekend, doesn't hold the lead.
When Brian Harman's dad dropped him off at football practice when he was a kid, the elder Harman told him not to be disappointed if he didn't get to play a lot. Thirty-two golfers shot under-par on Saturday, presenting a Round 4 where none of the top-16 golfers have won a major championship.
After a record number of scores under par during Thursday's first round, anyone who knows the USGA's style knew things wouldn't be quite as simple in Friday's Round 2.
Thomas has all the momentum, though. He bogeyed the 11, 12 and 13 holes and missed an easy birdie putt on the par five 14.
"I was upset with the score I had made, but it had, in no way, any effect on my attitude or how I was going to then approach the rest of the round or the next shot". First was this absurd putt on the 5th hole, where he lined up facing away from the hole and used the slope to sink a birdie.
"It means I'm a part of history", Thomas said after his round.
"Pitchers have good days and bad days, and I took an L [loss] today and come back tomorrow and try to finish this round strong going into next week".
The historic round also took Thomas, a three-time victor on the PGA Tour this season, to 11-under for the championship and a two-shot lead over compatriot Brian Harman and Englishman Tommy Fleetwood, still on the course.
Harman has history playing against him in the final round.
Nick Rogness felt as nervous as anyone at the U.S. Open - not because of a golf club in his hand but the diamond ring in his pocket.
With the entire field separated by just eight shots after the cut fell at one over, 2015 victor Jordan Spieth had hoped to get himself into contention, but struggled to a 76.
Thomas' lead heading into Sunday's final round?
Those are just a few of the possible winners. "So you've got to minimize those mistakes, minimize those bogies". 208: Russell Henley (USA) 71 70 67, Charley Hoffman (USA) 70 70 68, Patrick Reed (USA) 68 75 65.209: Brandt Snedeker (USA) 70 69 70, Brendan Steele (USA) 71 69 69, Bill Haas (USA) 72 68 69, Xander Schauffele (USA) 66 73 70.
England's Paul Casey featured in a four-way tie at the top of the 117th US Open leaderboard on Friday as the big guns crashed out of contention. This field is wide open, and full of guys without a major to their name.
"Well, it would change my life", he said.