Poulter updated his status on his Twitter account, posting Wednesday night that he had a temperature of 101.2 degrees and was "freezing then sweating." Then, Thursday morning, he posted about his withdrawal.
"Sorry guys never been so disappointed in pulling out of a tournament. Never felt so ruff, Hope 1st reserve plays well in a great group today," Poulter wrote.
Poulter, who won the 2010 WGC-Accenture Match Play Championship and is an 11- time winner on the European Tour, was replaced in the field by Miguel Angel Carballo.
Additionally, Alex Cejka withdrew with an elbow injury and was replaced by Richard H. Lee.