Woods was not completely happy despite shooting a 68

Tiger Woods overcame a problematic swing to take a share of the lead in round two of the Wachovia Championship in Charlotte, North Carolina.

Woods shot 68 to go six under alongside Fiji's Vijay Singh, who fired a 71, and Arron Oberholser (69) of the USA.

Overnight leader Padraig Harrington went out later on Friday and slipped back to three under with a disastrous triple-bogey seven at the last.

"I was struggling with my swing a little bit," said Woods.

The world number one found just five fairways but only dropped a stroke on his final hole as his accurate short game came to the fore.

And his score of 68 still matched the best round of the day.

"I had to keep focus on what I was doing. I didn't hit it very well and I've got to go fix a few things but I'm very pleased with my score," he added.

"I felt like I pretty much have maximised my two rounds here."

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For a while it looked like Harrington would end the day in front.

The Irishman made a poor start with three bogeys in the first four holes, but fought back with four consecutive birdies starting at the 10th.

However, he fell back into tie for the lead with a bogey at the tough par-three 17th and slipped back down the leaderboard after driving into a bunker, pulling his second into the water and then three-putting on the 18th for a round of 75.