Harrington had a disappointing final round last week at The Belfry and let the International Open slip from his fingers. However, he managed to put those thoughts aside Thursday under cold and windy conditions at Gut Kaden.
'What a difference between rounds,' said Harrington. 'It got to a stage out there that I didn't even bother reading the putts. It didn't seem to make a huge difference whether I read them well or read them badly, hit them well or hit them badly, they still went in.'
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The Irishman played the back side first and collected a pair of birdies starting at the 12th. Harrington birdied the 15th and hit his tee shot inside 16 feet at the par-3 16th to move to four-under.
Harrington reached the green in two at the par-5 third en route to another birdie and knocked his second shot to three feet for a birdie at the eighth. At the par-4 ninth, Harrington hit his approach within 10 feet of the hole and drained the putt to secure a piece of the early lead.
Goosen jumped out of the gate with three consecutive birdies from the first and added birdies at the seventh and the ninth to make the turn at 5-under.
He made a birdie from off the green at the 12th to pull within one of the lead and joined Harrington in first with a birdie at the 15th.
Goosen, who has yet to win this season, then got up and down for a par at the last for a flawless 65.
'You always want to defend any title and obviously the Order of Merit title is the toughest one to defend because you've got to play well the whole year to try and win it,' said Goosen, who has finished atop the money list in each of the last two years. 'I am playing enough over here and if I play well enough I will try and give myself a chance by the end of the year.'
Woods, who is making his first appearance since the Masters, also started on the back nine and got things going with a seven-foot birdie at the par-3 14th. He then chipped his third shot to three feet for a birdie at the par-5 15th.
On the inward half, Woods found trouble at the par-5 third when his second shot found the water. He managed to reach the green in four and drained a 15-foot putt to save par.
Woods then picked up a birdie at the following hole on his way to a bogey-free 69.
'Just a case of trying to shoot under par the way the wind's blowing out there and it's a tough day,' said Woods, who has won this event a total of three times. 'Overall I'm fine. I got a good night's sleep last night and got up this morning ready to play.'
While the top player in the world braved the conditions, he had plenty of praise for playing partner Harrington.
'He putted beautifully,' said Woods. 'I think he is just more consistent then he used to be. He's worked pretty hard and is now showing the results of the last few years.'
Darren Clarke had a steady front nine with three birdies and two bogeys. He bogeyed the second, his 11th, to fall back to even par before going on a run down the stretch.
Clarke birdied the third and hit his approach to seven feet for a birdie at the fourth. At the par-3 fifth, Clarke knocked his tee shot to five feet to make it three in a row.
He added back-to-back birdies from the eighth to close out a round of 67. Clarke was joined by Peter Lawrie and Peter Baker in a tie for third.
Andrew Coltart, Raphael Jacquelin, Christian Cevaer, Anders Hansen, Benn Barham, Niclas Fasth, Robert Karlsson, Warren Bennett and Miguel Angel Jimenez finished one shot further back at 4-under-par 68.
Colin Montgomerie, who lost to Woods in a playoff at this event last year, joined Woods in the group at 3-under-par.