Luke List and Jamie Lovemark moved into a share of a one-stroke lead at a windy Honda Classic as Rory McIlroy shot a second consecutive 72 to sit seven off the lead.
The leaders reached the halfway mark on three-under-par 137 with Tiger Woods also in contention on a tightly packed leaderboard despite dropping three shots in two holes on his back nine at the PGA National in Palm Beach Gardens, Florida.
Woods was left to rue a late lapse that left him four shots off the pace after he signed for a one-over 71.
"Two bad swings and it cost me three shots," the 14-times major champion told Golf Channel after an errant tee shot led to a double-bogey five on the par-three 15th, which the American followed with a bogey five on the next hole.
However, the 42-year-old former world number one birdied the 17th and closed with a par to sit in a tie for 14th in his third tournament of 2018 as he continues his latest comeback following back surgery last year.
"It's a strong test right now," said Woods, who also had two birdies and a bogey on the front nine to sign for a one-over-par 141 total after 36 holes in testing conditions, particularly on the greens.
"It feels good," he said. "I feel solid. I feel I am making some good passes at the golf ball and I've got pretty good pace on the greens, except for that putt at 16."
Early starter List made five birdies in a four-under 66 to surge up the leaderboard with the low round of the day after he had opened with a one-over 71 on Thursday.
Fellow American Lovemark later shot a 69 for a share of the halfway lead.
McIlroy was left to rue a triple bogey on the 17th hole which saw him plummet down the leaderboard while Shane Lowry was the only other Irishman to make the cut at the event.
Like McIlroy, Lowry also hit a triple bogey during his round, with his coming on the par-4 sixth hole. The Offaly man eventually signed for a 74 which left him on +5, just making the cut.
Graeme McDowell (77) finished on +7, with Seamus Power (74) on +11, one shot ahead of Padraig Harrington who shot a second round of 76 to finish on +12.