DUBAI, United Arab Emirates — Ian Poulter let the ball slip out of his hand, and with it went the Dubai World Championship.

Sizing up a 30-foot putt in the playoff, Poulter dropped his ball on his marker, moving it and incurring a one-stroke penalty that effectively gave the victory to Sweden’s Robert Karlsson.

The bizarre turn of events Sunday at the $7.5 million, season-ending tournament was the climax of a day which saw as many as four players challenging England’s Poulter for the lead. The 41-year-old Karlsson caught Poulter with a dramatic birdie on the 18th hole after he chipped within a few feet of the pin.

Karlsson calmly rolled in his short putt on the second playoff hole for the victory, his 11th on tour. He earned $1.25 million with the win while Poulter came away with $833,000.

Poulter, a colorful personality on the European Tour best known for his flashy attire, seemed as surprised as anyone by the gaffe. He described afterward how the ball slipped from his hand and fell two or three inches onto the marker — a lucky coin featuring his children’s names — causing it to flip over and move from its original position.

“The coin was one way and the next minute facing the other way,” Poulter said. “It’s pitched right on the front and flipped over. If it pitches in the middle, the coin doesn’t move and it’s fine. But it’s pitched on the front and it’s flipped over.”