Haas leads Masters on day one
American Bill Haas fired a four-under-par 68 to claim sole possession of the lead after the opening round of the Masters at Augusta.
On a day when fine weather conditions were counter-balanced by some tough pin placements, only four players were able to break 70 with Haas chief among them.
However, the 31-year-old is keeping good company with the two previous champions Adam Scott and Bubba Watson alongside 2012 runner-up Louis Oosthuizen a shot off the lead.
Haas had never broken 70 in 16 previous rounds at the Augusta National but gradually worked his way to the top after dropping a shot at the first hole.
He arguably made his round by playing Amen Corner under par, where both Scott and Oosthuizen found Rae's Creek.
Haas picked up birdies at 13 and 14 and although he gave one back at the 17th a fine approach to the closing hole set up a sixth birdie of the day.
"I made some nice putts early, a 15 footer on two that settled me down a bit and a birdie at the fourth that felt like an eagle," he said.
"A nice par save on five and the putter was hot, I also hit some good shots down the stretch.
"I've never broken 70 so I'm ecstatic to shoot 68 today."
Scott, looking to become only the fourth back-to-back winner in Masters history, enjoyed a fine round that was marred only by a miscalculated tee-shot at the short 12th that resulted in a double-bogey.
Oosthuizen, like Scott, recovered from an opening bogey before closing with a birdie to put himself right in the mix, while Watson struck a composed figure as he ground out an impressive bogey-free round.
A group of seven players are two shots off the pace including Sweden's Jonas Blixt, one of only four to reach four under par during the day before giving two back late on.
Fellow debutants Kevin Stadler and Jimmy Walker are also on two-under with Gary Woodland, KJ Choi, Marc Leishman and Brandt Snedeker, while Miguel Angel Jimenez of Spain heads a group on one-under.
Jimenez, playing alongside Haas, led the way after reaching the turn in four under par, but a bogey at the difficult 11th was followed by a double when he too dumped his tee-shot at the next in the creek.
But the 50-year-old parred in for a 71, a number matched by Rory McIlroy and fellow Briton Stephen Gallagher, also making his debut.
McIlroy had found the green at the tricky 12th but three-putted, however he recovered with birdies at the 13th and 15th only to give another shot back at the final hole.
Lee Westwood disappointingly dropped two shots in the final five holes to return a 73 but several of the big names could struggle to contend over the weekend.
Phil Mickelson had a double and a triple bogey in his round of 76, which was matched by playing partner and reigning US Open champion Justin Rose and Ian Poulter.
Former champions Angel Cabrera and Zach Johnson returned 78s, while Luke Donald struggled to a 79 that saw a double bogey at the ninth changed to a quadruple after he was deemed to have grounded his club in a bunker.