Padraig Harrington got off to a slow start at the Shell Houston as he warms up for next week's return to Augusta National.

The three-time Major winner carded a one-under-par 71 in his opening round after bogeying three of his final six holes, leaving him in a tie for 65th spot and eight shots off the lead of Scott Piercy, who tied the course record he shot a nine under par 63 in Texas.

Piercy played a bogey-free round and leads a field which contains only two of the top 10 in the world — Sergio Garcia and Jordan Spieth.

Piercy holds a two shot lead over German Alex Cejka and J.B Holmes, while Luke Guthrie, Charles Howell III, Shawn Stefani and Phil Mickelson all finished on six under, with the latter looking in fine fettle as he looks to win a fourth Masters title next week.

Starting on the back nine, Piercy was three under on the turn before he really turned on the style.

Consecutive birdies from one through to four put him amongst the contenders before another under par score on six followed by 31 foot birdie on nine saw him to nine under.

Piercy, who has two tour titles to his name, hit 17 of 18 greens in regulation and was understandably delighted when talking to PGA Tour Radio afterwards.

“It’s great. I hit them really close on 15 of them, the last one was a cherry on top, overall it was really solid,” he said.

“The fairways are soft, the greens are receptive, there’s not too much wind, I hit it close a lot, I had 10 footers half the day.

“I felt good with the putter which is good because I had felt a little off.”

Cejka made four birdies in his nine holes including an 18-footer on the 16th. Under par scores followed on one, two, four and eight, but his round was soured slightly by a dropped shot on nine.

Holmes made the perfect start with an eagle on one before further under par scores saw him to six under through his first nine. An unspectacular front nine which saw two birdies and a bogey at the par four six sees him in contention.

Mickelson shot five under on his first nine, his lowest round since January, and his form will be pleasing especially as he yet to finish better than 17th in six starts this season.

“This is a big week for me,” Mickelson said. “I felt the game was close last week. The only thing missing was chipping and short game.

“If I can play well this week or continue on playing for the next three days, it should be some good momentum for next week.”

England's Paul Casey, who will make his first Masters appearance next week since 2012 after he was named the 99th qualifier out of 99, had an encouraging round.

An eagle then birdie on four than five represented a solid opening nine for Casey, who won this title in 2009.

Another under par score on 12 was followed up by a 50-yard pitch shot on the par five which rolled into the cup for an eagle, before bogeys on 16 and 18 saw him finish the day in joint-15th.