Padraig Harrington’s not afraid of Tiger Woods but he knows he’s in for one hell of a battle when they duel it out for the WGC-Bridgetone Invitational at Firestone on Sunday.

Head to headIreland’s triple major champion shot a three under 67 on a showery day to lead by three shots from Woods on 10 under par and remain on track to create two new milestones in his career - his first wire-to- wire PGA Tour win and his maiden World Golf Championship to boot just days before his US PGA defence.

“I realise I'm going to have a difficult day, that's for sure,” Harrington said. “You know, this golf course has obviously been very good for Tiger (six wins from 10 appearances). He's played well on it in the past and done well, so I don't think anything is going to be easy tomorrow. Probably at best it's going to be a long, hard day and a battle. That's what I'm going to prepare myself for.”

Had the Dubliner culminated another wild-eyed back nine charge by holing a 15 footer for birdie at the 18th, the lead would have been an even more comfortable four shots over Woods, who birdied four his last seven holes for a 65.

When he realised he’d be playing with Tiger, he wished he’d holed it. As it is, a 69 would force Woods to shoot 65 to win.

“Until I holed out on 18. I looked up to see who I would be paired with tomorrow. That's all I was looking for. I had no idea. It was a surprise to see him there,” Harrington said.

Harrington thought he would be paired again with his Saturday playing partner, Tim Clark. Clark had been tied for the lead or trailing by one or two strokes throughout the day.

But Clark had long ago blown himself out of the tournament and then dropped from a tie for third place to a tie for 14th after he was handed a two-stroke penalty for failing to replace his ball on the 16th hole after moving it out of Harrington’s line.

Clark called the penalty on himself when he remembered at the 18th hole that he had forgotten to replace his ball at the 16th. He mentioned it to a PGA Tour rules official, who took him to the CBS TV trailer to review videotape of the hole. Clark’s round of 71 became a 73, and he fell seven strokes behind.

So how did Harrington feel when he saw Tiger’s name below his on the giant leaderboard at the 18th green? Shock? Surprise? Excitement even?

“I was surprised, yeah. I didn't know he was up there. Okay, he's in second place, there he is, 7‑under par, there you go, three‑shot lead, is that enough? Probably not.” He said to laughter from the press corp. “But now I really wish that putt went in on 18.”

Harrington knows what it’s like to beat Woods in the final round of a tournament. In 2002 he led Woods by six in the Williams (later the Target) World Challenge, extended that lead to eight shots but only won by a stroke after a stirring Woods comeback at Sherwood in Los Angeles.

In 2006 he did it again in the Dunlop Phoenix Tournament in Japan. This time Woods led by three with six to play but Harrington came up on the blindside to force extra holes and took the title with a birdie at the second tie hole.

“I kind of snuck up on him there. It was not quite beating him down the stretch,” Harrington recalled. “As I said, he just took the foot off the pedal there. Target was probably a more satisfying win. That was a bigger win in the States sort of thing, and he was pushing and I needed to stay ahead of him. That was probably the more pleasing. Both of them were very pleasing, but probably the Target was more character building.”

Harrington wobbled in LA seven years ago, but held on. On Saturday at Firestone he began with a one shot lead over Clark, extended it to two with a birdie at the opening hole and slowly lost confidence before finding it again thanks to some amazing recovery play and a red-hot putter.

Drives into the rough at the eighth, ninth and tenth could have derailed the Harrington express but he recovered with the kind of play that has become his trademark.

The pick of them was a low, hooking six iron from under the trees left of the ninth fairway. The ball finished 27 feet from the flag but could easily have run up and finished stone dead.

“I had a nice chance on 3. I hit a lobby bunker shot and was unlucky at 4, had a nice chance on 5, nearly holed a putt on 6. All of a sudden everything was going away from me. It's just not happening,” Harrington said. “Then I played 8, 9, 10 poorly, but I made three great saves. So now I think everything is going my way. If I hit it to 20 feet in those three holes and missed the three putts, I would have felt awful going down the 11th, but I felt great going down the 11th because of those three saves. I started playing well again and started holing the putts.

“Sometimes it's a nice thing when you get off the beaten track and you recover. You feel better about how you're scoring anyway, and that's ‑‑ obviously my mindset in the last nine holes was very good, very positive in that sense.”

Harrington has been a fragile giant this season because he has lacked the confidence in his swing to go for his shots without fear. Having neglected his short game to work on the latest adjustment to his ball- striking, he could never been sure he would get up and down for par if he took on a shot and failed. More often than not this season, he has could not paper over the cracks with a deadly short game.

Having found the way forward with his swing during a range session at the French Open (a change that has yet to be fully implemented), Harrington began work on his short game again before the third round of the Open at Turnberry and the reaped the fruits of his labours.

“When I was feeling good and started hitting a few good shots, I kept going after it,” he said. “I was feeling like things were going my way, and my focus was really in on the back nine. I was thinking birdies all the way home. I was pushing hard. It's just a little bit of a change of mindset, and sometimes that happens when you make a few recoveries; you feel a little bit more bullet‑proof, I suppose, and you go after a few things.”

He holed a 30 footer for birdie at the par three 12th, a 22 footer at the 13th and then hit the flag at the 15th before rolling in an eight footer to lead by three.

He bogeyed the par-five 16th, where his 108 yard approach bounded into the back bunker. Faced with a delicate splash shot, he came up short in the collar of rough and took six. But his response came in the shape of another birdie at the 17th, where a 20 footer disappeared to restore his three shot cushion.

Despite the good memories of his wins over Woods, Harrington knows it’s not going to be easy to get over the line.

“You just don’t know what’s going to unfold tomorrow,” Harrington said. “But obviously, at this stage, I know it’s going to be a difficult day.”

He added: “I do expect to have a tough day. Really, from the word go, it’s going to be a real tough day. Just the hype of it all, everything about it, it’s just going to be a lot of work tomorrow. At the end of the day, there is an intimidation factor there.”

Woods is probably the best front-runner in the history of golf, with a 36-1 record when he leads after 54 holes. In the 22 times Woods has been in second place going into the final round, he has won nine times.

Bidding for his seventh win in the Bridgestone, Woods owns Firestone.

“I’ve always felt comfortable here,” he said. “There’s no doubt. You know, this golf course, you’ve got to be very patient on this golf course. You’ve got to really hit your ball well, and if you do, you’re going to give yourself a lot of chances.

“You know, there’s just certain golf courses that fit your eye. It’s just hard to describe. That doesn’t happen every week, but there’s certainly some courses that I feel that way and this is one of them.”

Harrington added: “Tiger has been a prolific winner here. In many ways I'm building him up in my own head, if you know what I mean. That would make me come out buzzing tomorrow and fighting as hard as I can. I know I'm going to need to do that. Obviously he's had a great record here. I ain't going to get away with anything easy tomorrow. That's the key thought. I've got to have going out there is I'm not hoping that Tiger turns up and shoots 70. I'm preparing myself that he's going to turn up tomorrow and shoot 65. I've got to better that. That's the idea in my head. I've got to go out there and perform.

“The last thing I want to do is go out there hoping that he doesn't. I've got to pump up to myself and put in my head that I've got to go out there and play good golf if I want to win this tournament.”