Patrick Cantlay and Xander Schauffele fired a 4-under-par 68 in Friday's foursomes to move to 17-under and maintain their one-shot lead at the Zurich Classic of New Orleans.
The American duo had posted a tournament-record 13-under 59 in the opening round of fourballs at TPC Louisana and they'll attempt to go low again in that format on Saturday.
Their nearest rivals at halfway are Doc Redman and Sam Ryder along with England's Aaron Rai and David Lipsky.
Both those pairings fired five-under 67s in Friday's alternate shot to reach 16-under.
Defending champions Cameron Smith and Marc Leishman of Australia are six back while pre-tournament favourites Collin Morikawa and Viktor Hovland are eight off the pace.
Cantlay and Schauffele have been partners in both the Ryder Cup and Presidents Cup and their understanding of each other's games was again in evidence on day two.
Starting on the back nine they birdied three of the first four holes before adding two more gains coming home, dropping their only shot at 12.
Redman and Ryder went bogey free in their 67 while Rai and Lipsky had six birdies.
All four of those players are seeking their first win on the PGA Tour.
Two second-round leaders have won since the Zurich Classic of New Orleans became a team event in 2017: Jonas Blixt/Cameron Smith (2017), Jon Rahm/Ryan Palmer (2019).
Cantlay and Schauffele finished T11 on their debut appearance as a team in 2021.
Making his 799th official start, Jay Haas (playing with son, Bill) became the oldest player to make a PGA Tour cut at 68 years, 4 months, 20 days.
Two of the previous four winning teams have come back from four or more strokes after 36-holes: Scott Piercy and Billy Horschel were seven behind in 2018 while Leishman and Smith were four adrift last year.
A look at what the leading pairs said after round two.
Xander Schauffele & Patrick Cantlay (59-68, -17)
Patrick Cantlay: "I think we just wanted to hit a bunch of quality golf shots, and we did that today. We really fought hard and made a bunch of those mid-range putts, especially in the middle of the round, and that kind of kept the momentum going.
"It's kind of tricky out there with the wind how it is, so I thought we played a nice round today."
Xander Schauffele: "We've played so much together that we're pretty aware of the dos and don'ts and we've seen it all. There's not too much conversation. We kind of got all that out of the way in the past couple years."
Aaron Rai & David Lipsky (61-67, -16)
Aaron Rai: "We played really well together. David hit some very good shots early on. I made a couple of putts and we kind of got the round going quite early. A couple of good saves, as well, so just very solid, created a lot of chances.
"David rolled some amazing putts, as well, throughout the whole of the round. Very close on a couple of the holes on the back nine. Gelled together very well, played very well. Tricky conditions, as well, so very pleased with how it went today."
David Lipsky: "Aaron sort of saved my ass the first nine holes. He was holing those putts early. It got the momentum going, and I was able to get some confidence going on the back nine, and we played great.
"I think between us we only missed like two greens and we hit almost every fairway, so I think that will do it in alternate-shot."
Sam Ryder & Doc Redman (61-67, -16)
Sam Ryder: "It's awesome. That's a good goal to have. Being bogey free in this format is just… you have a tendency, I think, sometimes to try harder because you're not just kind of feeling like you're letting yourself down, you're trying almost a little harder for your teammate.
"He's swinging it great, putting me in good positions off the tee, playing from the fairway, chipping it nice a couple times when we had to, and everything has just been solid. It's just been as stress free as it can be in this kind of format."
Doc Redman: "We played really solid last year (tied 17th), specifically in alternate-shot, so I think we just had a ton of confidence on that. We kept the same tees because there's some tough par-3s out there, he hits them great. So we're just kind of building off that."
No worries for Cameron Smith
Rolling back the years
Talor made to look easy
Lowry's tee-shot has a look
Happy Earth Day