RIO GRANDE, 6 Mar 2015 (AFP) - Cejka stood on seven-under 137 after 36 holes at Trump International with Hagy one back after his own 67 and Argentina's Emiliano Grillo third, two adrift after a 70.
While the world's top-ranked players compete at the World Golf Championships event this week at Doral in Miami, the US tour's lesser-lights are vying for a $540,000 top prize.
Cejka began on the back nine and birdied the par-5 15th and 18th holes, then birdied the par-5 fifth and followed with birdies at the seventh and ninth to close out a bogey-free day.
Cejka, whose most recent of four European Tour wins came at Trophee Lancome in 2002, has never won a US PGA title, notably squandering a five-shot lead entering the final round of the 2009 Players Championship.
Hagy, making only his third PGA start, made five birdies on the front nine and opened and closed the back nine with birdies around bogeys at 14 and the par-3 16th.
Seven players shared fourth on 141, including Australian Rod Pampling and Zimbabwe's Brendon de Jonge, the top-ranked player in the field at 87th in the world.
Two-time major champion John Daly was among 10 others another stroke off the pace.
Leading scores after Friday's second round of the $3 million US PGA Tour Puerto Rico Open (USA unless noted, par-72)
137 - Alex Cejka (GER) 70-67
138 - Brandon Hagy 71-67
139 - Emiliano Grillo (ARG) 69-70
141 - Jonathan Byrd 70-71, Chesson Hadley 71-70, Brendon de Jonge (ZIM) 71-70, Scott Pinckney 70-71, Joe Curran 70-71, Rod Pampling (AUS) 70-71, Glen Day 73-68
142 - Chad Collins 70-72, Gonzalo Fernandez-Castano (ESP) 73-69, Billy Mayfair 69-73, DJ Trahan 72-70, Bobby Wyatt 74-68, Chris Smith 69-73, John Daly 72-70, Guy Boros 73-69, Mark Hubbard 68-74, Ryan Armour 73-69
143 - Scott Brown 73-70, Daniel Chopra (SWE) 74-69, Shaun Micheel 71-72, Michael Bradley 71-72, Eric Axley 71-72, Oscar Fraustro (MEX) 72-71, JJ Henry 70-73, Andrew Svoboda 71-72, Lee Janzen 72-71, Fabrizio Zanotti (PAR) 72-71