Happiness is a long walk with a putter but the idyll lasted just 12 holes for Pádraig Harrington as he was forced to settle for a one under 71 in the opening round of the Shell Houston Open.

The Honda Classic winner wielded his putter like a magician for most of the day, rolling in putts from 12 feet, 11ft, 32ft, 15ft, 6ft, 9ft and 4ft on the front nine alone to be out in two under 34.

His only mistake was a bogey at the third, where he missed a 15 footer for par after overshooting the green. But having holed some 90 feet worth of putts on the front nine, Ireland's triple major winner dropped a 41-foot bomb for birdie at the 11th and a nine footer at the 12th to get to four under par. 

The statistics showed he had gained nearly five stokes on the field with his putter alone but he couldn't keep the magic going on the homeward stretch.

Back to back bogeys at the par-five 13th, where he had penalty drop off a pulled approach, and the par-three 14th (three putts from 55 feet) left him just two under.

In fact, in the end he did well just to drop one shot after a hook off the tee at the par-four 17th forced him to chip out backwards and hit his third from 240 yards.

The 43-year old ended the day tied for 65th with European Ryder Cup skipper Darren Clarke, who was three under with three to play but bogeyed the par-three 16th (bunkered) and the tough 18th, where he three-putted from 80 feet.

Scott Piercy fired a nine under 63 to lead by two from JB Holmes and Alex Cejka with Phil Mickelson (66) tied for fourth.