DORAL - American Patrick Reed became the youngest winner of a World Golf Championship event when he held on for a one shot victory at the Cadillac Championship on Sunday after an ailing Tiger Woods failed to mount a challenge. Reed shot a final round of even-par 72 to finish the $9 million tournament at four-under 284, one shot clear of Bubba Watson and Jamie Donaldson. It was Reed's third PGA Tour title in eight months."I was hitting the ball so good this week and my putting was just outstanding," said Reed. "Whenever you come to an event and feel very confident with your putting, a lot of pressure on your full swing comes off your shoulders. Around a golf course like this you have to be confident and I feel like I've done that really well." The 23-year-old began the final day with a two-stroke lead and quickly built up a commanding four-shot cushion before fighting off a late challenge from Donaldson.The Briton birdied the 17th hole to close within one shot of Reed. But when Donaldson bogeyed the last after finding a greenside bunker with his approach shot, Reed was able to lay up and seal victory with a bogey. Donaldson (68) and Watson (70) finished tied for second at three-under but no-one else finished the tournament under par. Woods had moved into contention on Saturday with a third round 66 to start the final day three shots behind but returned a six-over 78 to finish tied for 25th.The world number one did not make a birdie and walked gingerly off the course on Sunday with his health once again a concern ahead of next month's Masters. Woods arrived at Doral with his fitness in question after he pulled out of the final round of the Honda Classic a week earlier with back spasms and was grimacing in pain as he completed the championship."It is back spasms, so we've done all the protocols and it's just a matter of keeping everything aligned so I don't go into that," said Woods. "It's basically started on six, the second shot out of the bunker, my foot was out of the bunker. That's what set it off and then it was done after that, just see if I could actually manage through the round keep the spasms at bay."Reed, wearing a red shirt and black slacks as Woods does in his final rounds, displayed the same steely nerve as the world number one as he worked his way around the redesigned Blue Monster course and then showed he did not lack for confidence after he had won the tournament."I've worked so hard, won a lot in junior career, did great things in amateur career and now I have three wins on the PGA Tour," said Reed, who has already secured an invitation to play his first major at Augusta National next month. "I just don't see a lot of guys that have done that besides from Tiger Woods of course and all the legends of the game. I believe in myself, especially with how hard I've worked, I'm one of the top five players in the world. To come out in a field like this and hold on wire to wire, I feel like I've proven myself."Reed, who replaced Woods as the youngest WGC winner, got off to fast start with a birdie at the first hole before giving the stroke right back with a bogey at the second. However, Reed responded with back-to-back birdies at the third and fourth holes then reeled off nine successive pars before suffering a wobble at the 14th when he missed a five-foot par putt. With the pressure mounting and his lead slashed to a single stroke, Reed held his nerve over the closing holes.He made pars at the 15th, 16th and 17th holes to head to the 18th with a comfortable two-shot lead that allowed him to play safely and win with a bogey. As Reed celebrated he was quickly joined on the 18th green by his pregnant wife Justine, who will return as his caddy following the birth of their first child.