The past double Dunhill Links winner ended the opening round of the 2018 Dunhill Links event tied with fellow Irishman Paul McGinley and three others and a shot behind the leading duo of England’s Matt Wallace and Aussie Marcus Fraser.
Harrington had been level par, thanks to two birdies and two bogeys after seven holes, before birdies 12th 15th and 16th holes.
“I’ve had 11 days not playing on a golf course and started hitting shots on Monday, so a couple of days hitting shots and my first round was on Wednesday, 11 days, and it’s completely different, hitting a golf shot, hitting one on the golf course,” he said.
“I thought I would never be ready for today but there you go, a little bit of focus, a little bit of, I suppose, being in competition, it sharpens you a little bit.
“I was really good mentally today, which I thought I was going to struggle, but yeah, happily surprised.”