Koepka and DeChambeau credit preparation as they top congested leaderboard with one shot lead over Phil Mickelson on first day of the Masters
Brooks Koepka and Bryson DeChambeau were playing in the final few groups of the day and took advantage of the soft course conditions to break free of a highly congested leaderboard at Augusta National with a pair of six-under 66s.
Justin Harding set the early pace and at one stage in the day there were nine players tied at the top on three-under-par, but it was the World No.4 and World No.6 who both caught fire on the back nine to lead the field on the opening day.
Bryson DeChambeau almost aced the par-three 16th, chipped in for birdie on 17 and hit the pin with his second shot on the par-four 18th on his way to setting the clubhouse target at six-under par.
He was soon followed by Brooks Koepka, who made four birdies in a row from the 12th and proved once again that he is not a man to doubt when it comes to major championship as he posted the only bogey-free round of the day.
"That was probably the best ball‑striking round I've had in a major championship," said Koepka. "I left myself with a lot of good looks. Hit a lot of good putts. Just didn't make too many. You know, kind of fell in love with the line there on 16, and 18, actually hit a good putt, just didn't drop.
"I was very impressed with putting the ball in the fairway. I drove it and I shaped it, flighted it, and coming into the greens, controlling the spin, trajectory, everything there was about as good as I could have hit it today."
Koepka was highly criticised for admitting he was out of sorts and had less distance off the tee last month in an interview with Golf Channel after he intentionally lost a lot of weight in a short space of time, but that didn't stop him stepping up his game on Thursday at Augusta National alongside the golfing scientist.
“I wanted to do it and try to lose some weight and maybe went about it a little too aggressively for just a long period of time and the intensity of what I was doing,” Brooks had said about intentionally losing roughly 24 pounds since November.
It's rumoured that the reason behind the weight loss was for the ESPN body issue, leading Brandel Chamblee earlier in Masters week to call it "the most reckless self-sabotage that I have ever seen of an athlete in his prime".
And heading in to the first major of the year, Koepka certainly looked out of sorts as he missed the cut at the Arnold Palmer Invitational and had two T56s at both The Players Championship and WGC Dell Match Play.
But the three-time major champion has time and time again proved that his preparation for major tournaments pays off, and he credited a difference in attitude towards the majors and how he prepares for his performance.
"I keep pretty much the same routine for all the majors," Koepka said about his preparation during a major week. "It's very simple. There's no added stress during the week. It's pretty much the same people that are staying with me.
"I just enjoy the big stage. I enjoy major championships. I mean, that's what you're remembered by.
"I think it's whenever I walk on the grounds. I get to whatever major championship it is and just when I arrive there, I just get a good feeling. I don't know ‑‑ I don't know how to explain it. I'm just dialed in and I'm focused the entire week. I try to relax Monday through Wednesday. I just play nine holes every day just to kind of save some energy, and by that time, I've probably already played the golf course a couple times.
"Here, you obviously know it a little more because we play the same one every year, but really just relax and try to focus on the little things, and here, just spend a little more time on the greens."
"I'm super aggressive at a normal event, and that kind of backfires sometimes. But at a major, just know there's 72 holes, so I kind of let things brush off my back a little bit easier. I don't take anything, I could three‑putt on 8; I mean, I just kind of, whatever.
"But in a normal event, that really would have drove me nuts. I would have been sitting there for probably five minutes trying to figure out what I did wrong. But I just let things go a lot easier and I'm just on to the next shot in majors."
As for comments on losing too much weight? He isn't bothered what anyone thinks.
"Well, I lift all the time. I lift too many weights, and I'm too big to play golf. And then when I lose weight, I'm too small. So, I don't know (laughter). I don't know what to say. I'm too big and I'm too small.
"Listen, I'm going to make me happy. I don't care what anybody else says. I'm doing it for me, and obviously it seems to work."
DeChambeau, who is widely dubbed as the 'Golf Scientist' and is renowned for his, also credited preparation and experience for his first round in the 60s at Augusta National.
"Well, you saw me working as hard as I possibly could leading up to this event," said DeChambeau about how he prepared in the lead up to the Masters. "I think a lot of the preparation is needed coming into this event.
"I think just experience over time, I don't know if I'm going to be able to figure out every little nuance of this golf course in my third year playing, but what I can do is prepare as good as I can and be comfortable with my own game in any situation; so that when I get out here, any situation that arises, I feel I can execute and play the game that's necessary.
"I had to spend more time on the putting green. Normally we have contour maps, and I'm able to rely off those pretty easily. Unfortunately we don't this week, and I understand that. Totally respect that, and you know, I like the challenge, actually. It's kind of fun. I think going out there and trying to use your eyes as much as possible, get your sense of balance and where level is, it's really a very unique skill. It's a tough skill to develop and create, but one that if you can do that, then in other tournaments, too, using the contour maps, you can be really deadly with both of that, combined together.
"But here this week, it's about really practicing and looking at slopes and making sure you can see the line go in the hole."
But more time wasn't the only preparation Bryson had: last week, he spent 14 hours on the range picking the best iron set up.
"Well, last week we spent a good deal ‑‑ and it started ‑‑ it's been going on for a couple years now with my wedge play and my iron play not being as good as I know it could be for the swing that I have.
"So everybody was like, well, its the one length ‑‑ it's not. It's something else that we were missing. And so last week I said I'm going to stay here at Dallas National until I figure out what it is on this gear system.
"I stayed there for 14 hours on Wednesday hitting 125 shots out there on this system trying to figure out what was happening with the wedges, and we knew it was something in regards to the spin loft curve and us being on the wrong side of the spin loft curve, but we didn't understand how to get it back on the correct side.
"And so after careful observation and some really deep, deep thinking about what's happening and some cool depictions of how the club was moving through the ball, we started to realize it was something we could do with the shafts. And so we went the other way with my previous logic, which I don't really want to give too much about it out, but we went the other way with the way I was previously thinking, and it actually started to work."
Phil Mickelson, who is aiming to become the oldest Masters champion in history this week, birdied three of his last four holes to finish one behind the leaders, with Dustin Johnson and Ian Poulter a shot further back.
Behind them, a group five players sit on three-under, while Tiger Woods and Rickie Fowler are among 10 players at minus 2.