Tiger Woods believes confidence is the key to  Padraig Harrington's transformation from serial runner up to multiple major champion over the past two years.

The pair will tee it up together in the Arnold Palmer Invitational at Bay Hill on Thursday with the world No 1 expressing his admiration for the Dubliner's work ethic.

Confidence is the key to Harrington's major success according to Tiger WoodsHarrington had more than 30 runner up finishes before he won the 2007 Open at Carnoustie and went on to retain the Claret Jug at Royal Birkdale and then claim the US PGA at Oakland Hills for back-to-back major victories.

Asked the key to Harrington's success in recent years, Woods said: "It's just confidence. Once you get it done once, it's amazing what that does for you.

"If you look at Paddy's career, all around the world, how many times did he finish second? But once he learned how to win, how many times has he won since?

"And once he won a major, he won two last year. It just shows you that you can do it.

"The way he came back after making a mistake at Carnoustie, his two back nines last year, I believe it was 32 on both of them. To do that on the back nine on Sunday of a major championship, that's awfully impressive.

"I think that's just his confidence. He works hard, there's no doubt, he's one of the hardest workers that we have in the game of golf.

"It's just a matter of proving to yourself that once you do it once, it becomes a little bit easier to do it again."

Woods won four majors in a row between 2000 and 2001 and knows that the gap between last year's US PGA and Harrington's bid for the third leg of the "Paddy Slam" at Augusta must feel like "an eternity" for the Irishman.

Asked what will be most difficult to handle, Woods said: "It's going to be the expectations, the responsibilities that come with winning two majors in a row, the questions he's going to get asked week in and week out.

"It has been months (of that) because of obviously the big break between the PGA and the Masters.

"I remember in 2000 going into 2001, the time that it took to get from the PGA to the Masters just seemed like an eternity because people kept asking questions each and every day about what do you think about Augusta.

"But that's just something that he's had to deal with. He's had plenty of months to deal with it and it's just right around the corner now."