Justin Rose squandered a four-shot advantage, then birdied three of the last six holes to seize a one-stroke lead after Friday's second round of the 85th Masters.
Charl Schwartzel was the best placed of the South Africans after he shot 71 to be eight off the pace.
The 40-year-old Englishman overcame a nightmare start to fire a level par 72 and stand on seven-under 137 after 36 holes at Augusta National.
"Today, ultimately, was a fairly good result in the end," Rose said. "To be honest, I felt comfortable and fairly confident all day.
"Making a few birdies just makes you feel good out there for sure."
Rose, twice a Masters runner-up, fired a 65 on Thursday to lead by four, matching the largest 18-hole Masters edge since 1941.
But the reigning Olympic champion began Friday with four bogeys in his first seven holes, briefly losing the lead before a sparkling late fightback restored him to the top.
"It was just a classic day at Augusta National. When you're just a foot or two off you can end up struggling," Rose said. "But I'm still leading so I'll enjoy it and keep going."
Will Zalatoris, who could become the first Masters debutant winner since Fuzzy Zoeller in 1979, and Brian Harman shared second on 138.
The US duo only qualified for the Masters off last week's world rankings, but one could take his first major title by winning the green jacket.
"Three weeks ago, I didn't expect to be playing in the Masters," Harman said. "So after a couple good days to be in contention is just icing on the cake for me. It's great. I'm going to try to put two more good ones together and see what happens."
Zalatoris birdied the last three holes to shoot 68 and likely put himself in Saturday's last group, while Harman birdied 17 and 18 to shoot 69.
"It's a childhood dream to be in the final group of a major on a weekend, especially here," Zalatoris said.
Three-time major winner Jordan Spieth, who snapped a four-year win drought last weekend, shared third on 139 with Australian Marc Leishman.
"Couldn't be more excited," Leishman said. "This is the position I wanted to be in. As long as you're somewhere near the top, anything can happen."
Spieth, a 2015 Masters and US Open champion, had not won since the 2017 US Open until last Sunday at Texas.
"If I can shoot 5-under on the weekend, that might be good enough," Spieth said.
A pack three back on 140 included second-ranked Justin Thomas, fellow Americans Tony Finau and Cameron Champ, Austrian Bernd Wiesberger, Japan's Hideki Matsuyama and South Korean Kim Si-woo.
Thomas could overtake Dustin Johnson for world number one with a victory.
Rose, whose only major title came at the 2013 US Open, opened with a bogey for the second consecutive day and answered with a birdie at the par-5 second.
Rose then made bogeys at the par-3 fourth and sixth and par-4 seventh. He missed the green at four, had a putt roll back to him at six and found a bunker at seven.
The world number 41 could only muster pars at eight through 12 after an eagle and three birdies Thursday, but those helped him "stop the rot," he said.
Rose had a tap-in birdie at the par-5 13th and holed a 20-footer to birdie the par-4 14th and reclaim the lead alone. He birdied the par-3 16th and closed with two pars to stand 9-under on the back nine for two rounds.
"I'm going to keep hitting shots," Rose said. "I'm not going to worry about a score."
Reigning US Open champion Bryson DeChambeau birdied three of the last four holes to stand on 143, finally finding form with his long-driving style.
"Anything can happen if I go 5-under, 5-under," he said. "I view it as I've got eight great shots at some par-5s if I hit the driver well. I make a couple birdies on some par-4s and take it easy on the difficult holes, I'll be fine."
Top-ranked defending champion Johnson made bogeys on three of the last four holes to finish on 149 and miss the cut, which came at 3-over 147 and left 54 players for the weekend.
Also missing the cut were four-time major winners Brooks Koepka and Rory McIlroy and England's Lee Westwood.
American Matthew Wolff was disqualified for returning an incorrect scorecard.
Second-round scores on Friday in the 85th Masters golf tournament at Augusta National Golf Club in Augusta, Georgia (USA unless noted, a-denotes amateur, par-72):
137 - Justin Rose (ENG) 65-72
138 - Will Zalatoris 70-68, Brian Harman 69-69
139 - Marc Leishman (AUS) 72-67, Jordan Spieth 71-68
140 - Bernd Wiesberger 74-66, Tony Finau 74-66, Justin Thomas 73-67, Kim Si-woo (KOR) 71-69, Cameron Champ 72-68, Hideki Matsuyama (JPN) 69-71
141 - Xander Schauffele 72-69
142 - Ryan Palmer 74-68, Collin Morikawa 73-69, Cameron Smith (AUS) 74-68, Corey Conners (CAN) 73-69
143 - Bryson DeChambeau 76-67, Matt Jones (AUS) 74-69, Stewart Cink 74-69, Viktor Hovland (NOR) 73-70
144 - Mackenzie Hughes (CAN) 72-72, Robert MacIntyre (SCO) 74-70, Shane Lowry (IRL) 71-73, Tommy Fleetwood (ENG) 74-70, Matthew Fitzpatrick (ENG) 74-70, Michael Thompson 72-72, Henrik Stenson (SWE) 73-71, Brendon Todd 73-71, Abraham Ancer (MEX) 75-69, Bubba Watson 74-70, Jon Rahm (ESP) 72-72
145 - Martin Laird (SCO) 74-71, Kevin Na 75-70, Gary Woodland 73-72, Tyrrell Hatton (ENG) 71-74, Scottie Scheffler 73-72, Charl Schwartzel (RSA) 74-71, Harris English 74-71, Patrick Reed 70-75
146 - Jose Maria Olazabal (ESP) 75-71, Louis Oosthuizen (RSA) 76-70, Jim Herman 76-70, Joaquin Niemann (CHI) 75-71, Christiaan Bezuidenhout (RSA) 70-76, Webb Simpson 70-76, Matt Wallace (ENG) 74-72
147 - Jason Kokrak 71-76, Francesco Molinari (ITA) 74-73, Billy Horschel 76-71, Phil Mickelson 75-72, Adam Scott (AUS) 74-73, Sebastian Munoz (COL) 74-73, Ian Poulter 74-73, Paul Casey (ENG) 73-74
The following players failed to make the cut
148 - Jimmy Walker 75-73, Matt Kuchar 78-70, Max Homa 74-74, Sergio Garcia (ESP) 76-72, Daniel Berger 75--73
149 - Mike Weir (CAN) 78-71, Lanto Griffin 76-73, Kevin Kisner 72-77, Danny Willett (ENG) 76-73, Brooks Koepka 74-75, Dustin Johnson 74-75, Lee Westwood (ENG) 78-71
150 - C.T. Pan (TPE) 79-71, Dylan Frittelli (RSA) 76-74, Robert Streb 75-75, Rory McIlroy (NIR) 76-74
151 - Victor Perez (FRA) 78-73, Zach Johnson 77-74, Bernhard Langer (GER) 74-77
152 - Brian Gay 78-74, a-Charles Osborne 76-76, Patrick Cantlay 79-73
153 - Carlos Ortiz (MEX) 82-71, Ian Woosnam (WAL) 76-77, Jason Day (AUS) 77-76
154 - a-Joe Long (ENG) 82-72
156 - Hudson Swafford 73-83, Sandy Lyle (SCO) 81-75
157 - Fred Couples 79-78, Im Sung-jae (KOR) 77-80
159 - Vijay Singh (FIJ) 79-80
161 - a-Tyler Strafaci 80-81
163 - Larry Mize 84-79
Matthew Wolff DQ