It's an All-England final in the first World Golf Championship of the year, with the winner assured of going to No. 5 in the world and collecting a $1.4 million check.
Poulter, who had plenty of rest after his 7-and-6 victory in the semifinal, built a 4-up lead through 14 holes when Casey struggled with his game and couldn't overcome mistakes with his putter. Casey won two of the last four holes in the Sunday morning session to close the gap.
Casey had to return Sunday morning to finish the semifinal over Camilo Villegas, winning his longest match of the week with a par on the 24th hole.
Villegas hooked his tee shot into the desert and was lucky to find the ball, which was in a bush 4 inches off the ground. He blasted it out into the fairway and wound up making a bogey. Casey chipped to 5 feet and made the putt for par.
Casey then left straight for the first tee for championship match.
Casey and Villegas had exchanged a series of great shots and clutch putts through 23 holes Saturday until twilight made it too dark to continue.