South African Retief Goosen defied a painful back ailment to fire a six-under 65 Saturday and seize a share of the third-round lead with Jim Furyk at the US PGA Tour Transitions Championship. Goosen's seven birdies on the Copperhead course at Innisbrook included three in a row from the 14th as he positioned himself for a run at a title that could earn him a Masters berth. Goosen, who said he would take next week off to have his aching back treated, needed just 25 putts on a course where he won titles in 2003 and 2009. He had an 11-under total of 202. He was joined there by Furyk, who gave up sole possession of first place with a bogey at 18 to cap his 66. The leaders were one stroke in front of American Jason Dufner and South Korean Sang-moon Bae. Bae had the lead until a triple bogey seven at the 16th. He responded with a birdie en route to a 68, while Dufner carded a 71 for 203. John Mallinger (66) and Ken Duke (69) were a further stroke back on 204. Goosen, ranked 52 in the world, could also book a Masters berth with a good enough finish to get into the top 50. His position atop the leaderboard seemed unlikely after the pain in his back flared up last month after he kicked a football around with his son. A bulging disk and a degenerating disk in his lower back had already caused him to miss two major championships last year. "It's not good," said Goosen, who has benefitted this week from the warm Florida weather. He said he plans to get a protein injection in his disks on Wednesday in Virginia. The treatment is similar to that received by Vijay Singh and Fred Couples in Germany. "The last three weeks, it's really just started getting bad again," Goosen said. "So hopefully, I'll be ready to get going again after the Masters -- or maybe the Masters, if I play well tomorrow," he said. Bae, a US tour rookie who made it to the quarter-finals of the World Golf Championships Match Play Championship last month, was five-under through 11 holes and had sole possession of the lead until Furyk caught him at 15. At the next, Bae drove into the trees as he tried to avoid the water on the right of the fairway. He pitched out, then hit over the green and three-putted. "So funny, my second shot a little far through the fairway," Bae said. "So the lie was very tough in the rough." Despite the big number, he said, "my chipping, putting, everything wasn't too bad." A trio of players on 205 included Chez Reavie, Ernie Els and Luke Donald. South Africa's Els, who probably needs a victory to get into the Masters, carded a 68. England's Donald, who could regain the world number one ranking with a victory, posted a 70 and Reavie a 67. In all, 26 players were within five strokes of the lead going into the final round.