There were surprises at both ends of the leaderboard at the conclusion of round two of the Farmers Insurance Open.
Gary Woodland and K.J Choi have replaced American duo Scott Brown and Andrew Loupe at the top of the Farmers Insurance Open leaderboard after two rounds following a dramatic day in which some big names failed to make the cut for round three.
American Woodland and South Korean Choi both carded five-under-par 67 to end the round at nine-under overall.
Woodland birdied five of the front nine, before shooting three bogeys and three birdies on the back nine of the South Course to complete his round, while Choi - who has not won on the PGA Tour in almost five years - kept pace with his fellow leader on the North Course to shoot his 67.
But while Choi's presence at the pointy end of the field was something of a surprise, it was nothing like the shock of Jason Day's exit, as the defending champion failed to make the cut of one-under.
He shot three bogies before shooting a birdie on the final hole, but it was not enough for the Australian.
Day became the first defending champion at the Farmers Insurance Open to not make the cut since 2003, but he was not the only high-profile professional to fail in making the cut.
Phil Mickelson also exited at the second round after shooting bogeys on the last three holes, while he and Day were joined by world number seven Justin Rose as he finished on par with 144 after two rounds.
Back at the other end of the leaderboard, Dustin Johnson sits in third after two rounds, at eight-under overall after a solid six-under.
The best score of the round was carded by Derek Fathauer who shot a seven-under 65.
He opened his round with three-straight birdies, and notched another three-straight on holes 14, 15 and 16, to add to his fourth of the day on the seventh hole.
Fathauer remains four shots off the pace.
Round one leaders Brown and Loupe sit in equal fourth and equal 27th respectively.
Loupe carded three-over-par in a tough day for the American, while Brown remains in touch with the leaders and will need to make up the two-shot difference over the remaining two rounds.