Louis Oosthuizen and Charl Schwartzel put together a 9-under 63 on Saturday to move to 19 under and take a narrow lead after three rounds at the Zurich Classic of New Orleans.
The pair of South Africans made nine birdies during the four-ball round one day after a much more muted 71, eking them ahead of the pack through 54 holes.
The PGA Tour's team event is anyone's game entering Sunday, with 16 other pairs of golfers within four strokes of the leaders. Sunday's round will be alternate-shot foursomes rather than four-ball.
"Look, it's going to be tough (Sunday)," Oosthuizen said. "I think anyone within four shots of the lead has got a chance with the format that it is (Sunday). It's going to be tough. We need to play really well."
A pair of Australians, Marc Leishman and Cameron Smith, and a pair of Americans, Cameron Champ and Tony Finau, each trail the leaders by one shot at 18 under. American tandem Bubba Watson and Scottie Scheffler, and Norwegian team Viktor Hovland and Kris Ventura are also in contention at 17 under.
Oosthuizen and Schwartzel began the round in a tie for fifth. They got things rolling on the back nine, where they sank six birdies to card a 30.
But Sunday's action, like the second round Friday, will have golfers alternate shots with their teammates throughout the day, creating tougher scoring conditions. No team scored better than a 4-under 68 Friday when those rules were first in effect.
Leishman and Smith combined for a 63 on Thursday and Saturday, just like Oosthuizen and Schwartzel -- but they only managed an even-par 72 on Friday. Leishman feels the team is ready to tackle the alternate-shot format in the final round, saying he "found something" on the driving range to improve his wedge play.
"But a lot can happen in foursomes, and so many other good players up at the top of the leaderboard," Leishman said. "A lot has to go right, but hopefully we can do our job and make some birdies and give the guys ahead something to think about."
Four other teams turned in 63s on Saturday: Thomas Pieters-Tom Lewis and Tyler Duncan-Adam Schenk, who are each tied for sixth at 16 under, and Wyndham Clark-Erik van Rooyen and Justin Suh-Doug Ghim, who are now tied for ninth at 15 under.
The Zurich Classic has only been a team event since 2017, when Smith won the title in a playoff playing with Jonas Blixt of Sweden. Smith said the course has undergone a lot of changes since that time, so the only advantage he believes he'll draw now will come from playing with a friend and countryman in Leishman.
"Obviously we've both been up at the top of leaderboards a fair bit lately, so I think just on our own experiences I think that'll help a lot," Smith said. "But we've just got to knuckle down and basically do what we did today. We played really good golf today."
Oosthuizen and Schwartzel each have a major title under their belts, but Oosthuizen -- despite being the No. 33-ranked player in the world -- has never won an event on American soil. Instead, he can claim the 2010 British Open and several victories in Europe, Africa and Asia. Schwartzel has the 2011 Masters to his name but hasn't won on the PGA Tour since 2016.
Oosthuizen said it "would be great" to snap their PGA Tour winless droughts on Sunday.
"I do think it's going to be still tough (Sunday). We need to really play well. If you look at that leaderboard, there's great players up there, especially with tomorrow's format. You know, I think we've got a good shot. We're playing really well. We're comfortable together. We just need to go do what we've been doing the last three days."
--Field Level Media