Well, who saw that coming?
With so many top players in the field, it wasn't inconceivable that one of them could get hot and pull five shots clear at halfway.
But that significant margin doesn't belong to one of the pre-tournament favourites. Instead, the fast pace is being set by a player only just inside the top 150 in the world rankings, American Sam Burns.
Rounds of 64-66 have catapulted him to the top of the leaderboard on 12-under. And that's the largest 36-hole lead in the tournament's long history.
He's had a halfway lead twice previously on the PGA TOUR but finished only tied seventh on both occasions. Can he keep it going this time?
Here's what Burns and some of the chasing pack said after Friday's play at Riviera.
Sam Burns -12 (64-66)
"I think just having patience out there. I didn't try to force anything. Whenever we were kind of in a tricky spot, just kind of took what the golf course gave us. I'd like to think that I have all the tools to win out here. Obviously there's a lot of good players, really, really good players. Yeah, I think try not to get caught up in that and just trying to get better each week and just trying to build as the season goes on."
"I thought four under's a really solid score around here anytime. I'm definitely pleased with it. Obviously still didn't play the par 5s quite as well as I'd like to, especially through the first two rounds. One under is not going to get the job done over the weekend. Definitely need to take advantage of the par 5s the next couple days. But other than that I feel like I'm swinging my irons really well, I'm rolling the putter nicely, so looking forward to the weekend. I like my position. I'm 5 back, but on this golf course there's only one guy in front of me. I like where I'm at and I do like this golf course, and hopefully I can drive it a little bit better on the weekend and give myself a few more chances."
Tyler McCumber -7 (67-68)
"I thought the course had some teeth today with some pins down the stretch, you definitely had to be on hitting your second shots. Fairways are firm, so if you kind of got it lower spin landing in the fairway, it would run forever, which was nice, allow you to get a little closer to some of these holes and have the numbers you wanted. Yeah, overall my play I felt pretty good about."
Jason Kokrak -7 (67-68)
"Pretty solid. A couple errant swings. Other than that I played very solid. Loose swing with the 3-wood on 11 kind of really didn't set my round out good, but nice birdie on the upcoming par 3 was nice. And I rolled in a couple nice putts, nice two-putt on 1 and then 2, 3 and 4 I made some really nice putts. Still another 36 holes left, a lot of golf left to be played and you've got to pick and choose where you're going to be aggressive and where you're going to play safe."
Joaquin Niemann -7 (67-68)
"It was a great round. Played similar to yesterday, hit the ball great. I feel that I putted really good, too, but they just didn't drop. There was some tricky putts out there. Yeah, it was a really good round. If I just keep playing the way I'm playing, I think I'm going to give myself a big chance. I just need to keep doing what I'm doing. I feel that all my game is on point. So yeah, just got to be patient. It's a really tough course so on the weekend anything can happen."
"All in all, very pleased with the ball-striking today. There's a couple wedges I could have hit in closer and then a couple kind of 10-foot-and-in birdie putts that I missed that you almost -- you know, when you have them out here, it's such a bonus, you're looking to cash 'em in. Yeah, I feel like today it was almost the highest score I could have shot and it's really a good sign for things to come. I made a couple iffy driver swings, but I actually drove the ball really, really well today until No. 9. Yeah, I mean, my ball-striking was really solid and my bogeys came from, you know, just being in the wrong place on 18, which can happen, and missed about a six-footer. Where was the other bogey? It was on 2 where I caught a jumper that I wasn't expecting. It was really nice today. I'm just going to try to look to continue what we did."
Max Homa -6 (66-70)
"It was good. I was patient. I did a lot of the things the same as yesterday. My touch wasn't quite as good around the greens, left myself too many six-to-eight-footers, but stayed patient, waited for some good numbers, took advantage when I had them at the end. Yeah, it felt very similar to yesterday, just kind of Riviera doing what it does. I've been playing some really good golf, so I'm just going to keep playing solid rounds."
Wyndham Clark -6 (67-69)
"I grinded out there today. I didn't have my best. I kind of had a shaky start and then even when I started making some birdies, I still wasn't hitting it great, I just kind of relied on my short game and putting today, which kept me in it. The score ended up being good, but I definitely didn't have my best. So going to go work on it and try to get it for tomorrow. I'm kind of slicing it right now and I ended up just playing it throughout the day, but I'd like to straighten it out. Tomorrow's supposed to be windy, so it would be nice to have my ball-striking tomorrow."
"I thought I struck it a lot better. I mean, the swings I made, the double I made and the bogeys I made were just because, I don't know, just I've had a stiff neck for like a month and a half and it just, I couldn't do it. But it's fine, I thought I struck it way better. I just got my neck popped, so it feels a million times better. Knee's good, there's no complaints. My body feels fine."
* Latest Paddy Power betting: 9/4 Sam Burns, 5/2 Dustin Johnson, 9/1 Joaquin Niemann, 12/1 Patrick Cantlay, 14/1 Jordan Spieth, 18/1 Jason Kokrak, 22/1 Brooks Koepka, 25/1 Max Homa, 33/1 Jon Rahm, Tony Finau