He missed a 15 footer on the last that would have set up a final round pairing with Tiger Woods had it gone in. 

No matter. Padraig Harrington recorded another rollercoaster performance in the BMW Championship at Cog Hill but his short game is so sharp that he still managed to shoot a two under par 69 that left him tied for fourth place with Matt Kuchar, eight shots behind Tiger.

Barring a collapse by Woods, who proved that his putting skills are as good as ever by carding a nine under 62 to take a seven stroke lead over Brandt Snedeker and Marc Leishman, overall victory is outside Harrington's compass.

Yet while he is eight strokes behind the world No 1, Harrington is projected to move up from seventh to fourth in the FedExCup rankings and that means that overall victory in the $10m series is still in his hands if he can maintain that position on Sunday and then win the Tour Championship in two weeks' time.

It is a tall order but Harrington is playing well enough to do it. The only question mark is his driving, which is ridiculously erratic.

On Saturday, he hit eight of 14 fairways, which was his best performance off the tee this week. But he still mixed six birdies with four bogeys.

One stroke off the lead held by Woods and Mark Wilson starting the day, Harrington holed from off the green for a birdie at the second, tapped in a four footer for another birdie at the third and then chipped in from deep rough at the fourth to take the lead.

Then came Tiger, who bogeyed the first hole before hitting eight birdies and an eagle in a textbook performance to win the tournament 24 hours ahead of schedule.

"I birdied 3, and next thing I know, I think Paddy birdied three of the first four, got off to a quick start," Woods said. "After seeing that and seeing what Marc was doing ahead of us, I just figured that you had to get into double digits today, and I thought that was going to be a good score to end up at." 

He's now 16 under par.

As Woods played the seven-hole stretch from the sixth to the 12th in five under par, Harrington played them in three over by mixing bogeys at the sixth, seventh, 10th and 12th and a solitary birdie at the par five 11th.

His bogeys came from a variety of mistakes. At the par-three sixth he was long in the back bunker and missed a 13 footer for his par. At the seventh he hooked his drive miles left, knocked his second shot 40 yards forward into a fairway bunker and had to get up and down from over the green for his five. 

A bad drive meant he  failed to birdie the 615 yard ninth, where Woods hit a 300 yard three wood to 10 feet and eagled. But what hurt him more were the bogeys at the par-four 10th and 221-yard 12th, where bad tee shots led to poor seconds.

In fact, he could easily have dropped another shot at the 13th, where he was in a fairway bunker off the tee but holed from 12 feet for par after an uncharecteristically sloppy chip from just short of the green.

He regrouped to birdied the 15th and 16th after hitting 150 yard approaches to around six feet each time. 

Woods will go top of the FedExCup rankings if he closes out his sixth win of the year on Sunday. If Harrington can remain inside the top four in Chicago, a first tour win of the season in Atlanta would be worth much gold.