Woods struggled on the front nine then produced five birdies in 10 holes
Tiger Woods birdied the last to share the lead with fellow American Nick Watney after two days of the HSBC Champions tournament in Shanghai.
Woods carded a five-under 67, while Watney followed his superb opening-day 64 with a second round 70 to head the field at 10 under for the tournament.
Watney struggled until the turn on Friday, but he and Woods each produced four birdies on the back nine.
Phil Mickelson, Ryan Moore and Spain's Alvaro Quiros are a shot back.
Anthony Kim, Pat Perez and Brian Gay lie behind Mickelson and Moore near the top of a US-dominated leaderboard in China.
German Race to Dubai contender Martin Kaymer fell away with a two-over 74 to drop six shots back, while European money list leader Lee Westwood is tied for 23rd place at three under after two solid but unspectacular rounds.
I knew if I could play the back nine at three-under par, that would be a good number - and I did a couple better than that
Fellow Englishman Ross Fisher bogeyed the last having found the water, dropping him to four under after two rounds, alongside compatriot Paul Casey and Kaymer.
Fisher was accompanied on his second round by Woods, who appeared angry at times on the front nine as he bogeyed the sixth.
But, like Watney, the 33-year-old found his game as the day progressed.
Having rolled a lengthy eagle putt to within a couple of feet of the 18th hole, Woods tapped in to take a share of the lead.
"It was certainly a little bit frustrating," Woods said of his start to the day.
"I knew that if I could just basically play the back nine at three-under par, I figured that would be a good number. And I did a couple better than that.
"I was surprised at how difficult the pins were. Consequently, the guys didn't go as low, but still there were plenty of opportunities out there."
"I knew from the start that Tiger and Phil were in the field and it's no surprise to see them playing well," said the 28-year-old.Watney, asked how he would fare with Woods and Mickelson in such close attendance, insisted the focus would be on his own game.
"I need to go out and keep making birdies to have a shot at winning."
Fisher was named the European Tour's golfer of the month for October after Friday's action in Shanghai had concluded.
In the wake of his victory in the Volvo World Match Play Championship, Fisher took the award ahead of Sweden's Michael Jonzon, who saved his Tour career by capturing the Castello Masters