WGC-Accenture champion Donald went into the final day knowing that he could leapfrog Lee Westwood at the top of the standings, something he has been trying to do for weeks, but he slipped to a 2&1 defeat to fellow Englishman Poulter at Finca Cortesin.
Poulter fell behind three times over the opening 11 holes but hauled himself level once again with a 40-foot putt at the par three-12th, and he went ahead two holes later.
Donald missed a three-foot putt as he three-putted the following hole, blowing the chance to pull level, and Poulter punished him with an approach to two feet that clinched the 16th hole before putting from seven feet to secure the victory.
The 35-year-old, who beat world number one Lee Westwood earlier in the competition, told europeantour.com: “I finally started holing some putts. I've been frustrated for a few months and you have to hole putts to win.”
Donald said: “It was disappointing. I ran out of steam a bit and didn't take the opportunities I had.”
