Tiger Woods blamed late season fatigue for his dramatic collapse over the closing stretch at the Tour Championship after he had surged into contention with five birdies in his first 13 holes. The American world number one, FedExCup points leader coming into last week and the title favourite at the PGA Tour's season-ending event, ended up one-over-par 71 on a sun-splashed day at East Lake. Woods, seeking his sixth victory this year but nine strokes off the pace overnight, ran up a double-bogey at the 14th, a bogey at the 16th and an ugly triple at the 17th as he finished well down the leaderboard at four-over 144. "I put everything I had into that start and didn't have much at the end," said Woods, who had declined to speak to reporters the previous day after opening with a 73. "Just ran out of gas. I'm tired." Asked whether he had suffered from physical fatigue, the 14-times major champion, who prides himself on his fitness and workout regimen, replied: "Yeah, definitely." Woods, who had experienced some back trouble during The Barclays, the first of the four FedExCup play-off events, was then asked if his back was okay. "It's been just a long, long grind," the 37-year-old American replied. "Everyone out here has got some knick-knack injuries, and guys are taped up and banged up a little bit. We have played a lot of golf from the British Open on." But he insisted: "I'm still in contention. There's 36 holes [still to play]." Five under for the day after 13, Woods' round unravelled in spectacular fashion. He double-bogeyed the 14th after hitting his tee shot way left, bogeyed 16 after finding the right rough off the tee, then butchered the 17th after his tee shot sailed well left into water to card a triple bogey. "My legs were just tired," Woods said of his tee shot at the 17th. "I didn't rotate through the ball and I turned it over. Same thing I did over on 14. Same shot."