(CNN) -- Padraig Harrington kept a charging Tiger Woods at bay on Saturday to take a three-stroke advantage into their final-round showdown in the WGC-Bridgestone Invitational at the Firestone Country Club in Akron.
Harrington leads Tiger Woods by three strokes going into the final round at the Firestone Country Club.
The Irishman, who will defend his U.S. PGA title later this month, shot a five-birdie, two-bogey 67 in the Ohio rain to lead the tournament on 10-under-par after six-time winner Woods fired a five-under-par 65 to move to seven-under-par -- setting-up a compelling last pairing for Sunday's final round.
"I'm obviously happy with my day's work," Harrington told reporters. "The key is to keep breaking 70 and make sure if anyone else is going to win this tournament they're going to have to play well.
"I realise I'm going to have a difficult final day, that's for sure. This golf course has obviously been very good for Tiger, he's played well here in the past and done well so I don't think anything is going to be easy."
Woods began the day five shots behind Harrington as he started his third round and was still four shots in arrears as he turned for home.
However, the world number one stepped up a gear on the back nine, four birdies in his last six holes moving him into a brief tie for the lead with Harrington and Clark.
Woods told reporters the difference between his second and third round was that he judged the speed of his putts better.
"Yesterday I didn't make anything, but I hit a lot of beautiful putts that didn't go in, because I didn't hit the putts hard enough," he said.
"I hit the putts a lot harder today. I drove the ball pretty good all day and hit some really good iron shots."
American Jerry Kelly lies in third place on five-under, where South Africa's Tim Clark was also positioned before calling himself for a two-stroke penalty after his round.
He failed to replace his ball in the original position on the 16th green, having moved it to allow Harrington to putt.
Clark fell back to three-under, one behind a group of 10 players including all three 2009 major winners -- Angel Cabrera, Lucas Glover and Stewart Cink. Spain's Miguel Angel Jimenez and England's Oliver Wilson are tied for seventh position on four-under-par.