Im Sung-jae shot a second-round six-under-par 64 to hold a share of the lead at the halfway stage of the Honda Classic at Palm Beach Gardens.
The South Korean followed up his opening 70 with a round with featured seven birdies and one bogey to head the leaderboard alongside American Keith Mitchell, who went round in 66.
Another American Lucas Glover was a shot further back after a 69, ahead of a group of nine players on four under, including three-time major champion Brooks Koepka, who also carded a 69.
Overnight leader Jhonattan Vegas could only manager a 73, making two double bogeys, as he slipped back to three under, alongside Sergio Garcia.
Graeme McDowell crept inside the two over par cut mark after rounds of 70 and 72. Seamus Power however did not, a seconr round of 78 leaving him well adrift on 11 over par.
The likes of 2012 winner Rory McIlroy and Tiger Woods are among the star names who have opted to skip the £5million tournament.
Collated second round scores in the The Honda Classic, PGA National (Champion Course) (USA unless stated, par 70):
134 Keith Mitchell 68 66, Sungjae Im (Kor) 70 64, 135 Lucas Glover 66 69
136 Adam Schenk 67 69, Sung Kang (Kor) 68 68, Adam Svensson (Can) 72 64, Kyoung-hoon Lee (Kor) 67 69, Danny Lee (Nzl) 69 67, Brooks Koepka 67 69, Wyndham Clark 69 67, Freddie Jacobson (Swe) 69 67, Ryan Armour 68 68
137 Peter Malnati 69 68, Benjamin Silverman (Can) 66 71, Charl Schwartzel (Rsa) 67 70, Julian Etulain (Arg) 67 70, Sergio Garcia (Spa) 67 70, Roberto Castro 67 70, Jhonattan Vegas (Ven) 64 73, Cameron Tringale 69 68, Anirban Lahiri (Ind) 67 70
138 Bud Cauley 67 71, Lucas Bjerregaard (Den) 70 68, Nick Watney 71 67, Zach Johnson 66 72, Matt Jones (Aus) 69 69 Vaughn Taylor 70 68, Chesson Hadley 68 70, Bronson Burgoon 67 71, Billy Horschel 67 71, Nick Taylor (Can) 72 66
139 Brian Stuard 69 70, Matt Wallace (Eng) 71 68, Daniel Berger 72 67, Vijay Singh (Fij) 70 69, Talor Gooch 71 68, Grayson Murray 71 68, Bill Haas 69 70, Ernie Els (Rsa) 66 73, Sebastian Munoz (Col) 69 70, Patrick Rodgers 68 71, Rickie Fowler 67 72
140 Jason Kokrak 69 71, Scott Brown 70 70, Sam Saunders 68 72, Chase Wright 72 68, Michael Thompson 71 69, Stephan Jaeger (Ger) 68 72, Max Homa 69 71, Tyler Duncan 69 71
141 Kramer Hickok 69 72, Harold Varner III 72 69, Brian Gay 71 70, Austin Cook 74 67, Ryan Palmer 70 71, Martin Kaymer (Ger) 71 70, Webb Simpson 72 69, Hank Lebioda 67 74, Russell Henley 69 72, JT Poston 73 68, Rory Sabbatini (Svk) 67 74, Harris English 70 71Joaquin Niemann (Chi) 71 70, Jim Furyk 69 72, Sam Burns 70 71Russell Knox (Sco) 69 72
142 Hudson Swafford 70 72, Roger Sloan (Can) 71 71, Byeong-Hun An (Kor) 74 68, Gary Woodland 72 70, Jim Knous 71 71, Richy Werenski 71 71, Justin Thomas 68 74, Graeme McDowell (NIrl) 72 70, Jason Dufner 73 69, Stewart Cink 71 71, Cameron Davis (Aus) 70 72, Kevin Streelman 72 70, Jonas Blixt (Swe) 70 72, Drew Nesbitt (Can) 71 71, Trey Mullinax 70 72, Ryan Blaum 69 73, John Huh 70 72
143 Austen Truslow 73 70, Carlos Ortiz (Mex) 71 72, Chris Kirk 75 68, Adam Scott (Aus) 72 71, Sepp Straka (Aut) 73 70, Brandon Hagy 72 71, Kyle Jones 72 71, Ben Crane 68 75, J.J. Henry 74 69, Whee Kim (Kor) 72 71, Denny McCarthy 70 73, Adam Long 72 71, Jim Herman 72 71
144 David Pastore 75 69, Ollie Schniederjans 71 73, Andrew Landry 73 71, Anders Albertson 70 74, Brady Schnell 76 68
145 Shawn Stefani 71 74, Scott Piercy 72 73, Tom Hoge 72 73, D.A. Points 72 73, Scott Langley 71 74, Cheng-Tsung Pan (Tai) 71 74, Martin Trainer 69 76, Dylan Frittelli (Rsa) 72 73, Johnson Wagner 73 72, Brandon Harkins 78 67
146 Luke List 71 75, Roberto Diaz (Mex) 72 74, Jimmy Walker 73 73, Patton Kizzire 74 72, Seth Reeves 72 74, Brice Garnett 73 73, Alex Prugh 71 75
147 Emiliano Grillo (Arg) 71 76, Cameron Smith (Aus) 68 79, Erik Compton 73 74, Morgan Hoffmann 71 76, Jose de Jesus Rodriguez (Mex) 73 74, Brian Harman 76 71
148 Hunter Mahan 75 73, Joel Dahmen 72 76, Kevin Tway 71 77
149 Satoshi Kodaira (Jpn) 72 77, Alex Noren (Swe) 77 72, Mackenzie Hughes (Can) 76 73
150 Kiradech Aphibarnrat (Tha) 75 75, Kyle Stanley 74 76, Joey Garber 73 77, Curtis Luck (Aus) 74 76, Kelly Kraft 76 74
151 Blayne Barber 73 78, Seamus Power (Irl) 73 78
152 Brendan Steele 75 77, Rod Pampling (Aus) 77 75
155 Cody Gribble 77 78
157 Robert Streb 75 82, Andrew Filbert 80 77
Cut to take place at end of Round 2 for scores of no more than 142
