Jason Day sank a 12-foot birdie putt at 17 and rescued par from a bunker at 18 Sunday to win the PGA Arnold Palmer Invitational by a single stroke. The 28-year-old Australian became the first wire-to-wire winner at Orlando's famed Bay Hill layout since Fred Couples in 1992, just weeks before Couples went on to win the Masters. Day, who rose to world No. 2 with the triumph, hopes to fit himself for a green jacket at the year's first major tournament in three weeks after collecting the trophy from Palmer, an Augusta National legend. "It means the world," Day said of the victory. "I just ground it out today. It wasn't the best I had but I got it done when I wasn't quite on." Day fired a two-under par 70 to finish on 17-under 271, defeating American Kevin Chappell by one with Sweden's Henrik Stenson and American Troy Merritt sharing third on 274 after battling Day throughout the final round. Day collected his eighth PGA victory, his first since last September's BMW Championship and his fourth in a row when leading after 54 holes. But it was intense. Stenson, Day and Chappell shared the lead at 16-under with five holes remaining, four of them playing among the course's five toughest, and Merritt was only a shot adrift after four back-nine birdies in a row following a double bogey at the ninth. Merritt blasted in a 43-foot shot from a greenside bunker at the par-3 14th for his fifth consecutive birdie to grab a share of the lead with Day and Chappell at 16-under after Stenson stumbled with a bogey at 14 and another at 16 after finding the water. Chappell missed a 26-yard eagle putt at the par-5 16th but tapped in for birdie to grab the lead at 17-under. Day and Merritt each parred 16 then shined at the par-3 17th, Merritt holing a 12-foot chip shot for par and Day sinking a 12-foot birdie putt to match Chappell for the lead. Chappell had gone into the right rough at 18 and evaded a water hazard but came up short from 25 feet for par, a bogey ending his day at 16-under, one back of Day as the Aussie came to the last tee. Day found the right rough and then a bunker beyond the green while Merritt's hopes ended when his approach splashed down shy of the green. Day blasted 90 feet out of the sand and sank a four-foot par putt to win, denying Chappell his first PGA victory. Kim wins Cup in record fashion In Los Angeles, South Korea's Kim Sei-young matched Annika Sorenstam's 15-year-old record for the lowest 72-hole score in LPGA history Sunday, firing a 10-under par 62 to win the LPGA Founders Cup. The 23-year-old from Seoul completed four rounds at 27-under par 261 over the Phoenix, Arizona, layout to match the mark set by Swedish legend Sorenstam to win the 2001 Standard Register PING tournament at Moon Valley Country Club, also in Phoenix. "It's a dream come true," Kim said. World No. 1 Lydia Ko of New Zealand made a late charge to finish second on 266 with American Jacqui Concolino third on 268. — Agencies