The 40-year-old Irishman produced a storming finish thanks to a red-hot putter as he birdied five of the last six holes, to charge from one over for the tournament to four under.

The three-time major winner had earlier produced a mixed bag with three bogeys and two birdies over the opening 12 holes.

"I did need it today to get into contention," said Harrington after signing for a four-under 68.

"It's the kind of back nine you dream of having on a Sunday at the Masters, but if I didn't do that today it wouldn't matter what I did tomorrow on the back nine.

"I did know I had to do something. Going out level par you just knew you had to do some of the work today.

"Four under is a nice score as long as the leaders don't get away. If the leader is only six under then you are right there.

"I'll play the same way tomorrow as today. I've been taking a good attitude to my short game and today I tried to take that into my long game and hopefully it will all be there tomorrow."