Casey rose to number three in the world rankings before injury last year
England's Paul Casey has pulled out of his defence of the Houston Open in a bid to be fit for next week's Masters.
The 32-year-old world number six has hurt his shoulder and neck and rather than risk aggravating the injury, he has withdrawn as a precaution.
Casey, who missed six months of 2009 with a torn rib muscle, said: "The injury is separate from last year's so I'm not overly worried.
"But the last thing I can do is try and push it. I hope it's a one-week thing."
Casey beat JB Holmes in a play-off to win his maiden PGA Tour victory in Houston last year.
But with the first major of the season starting next Thursday at the Augusta National, he has opted to rest.
"My left shoulder is not comfortable while my first rib on the left side is not moving correctly," Casey explained.
"The muscles around it have locked up so I am not able to get the club in a position where I can swing it properly and hit the golf ball.
"It feels like there's something pinched in my left shoulder as I am having difficulty moving my head and rotating my neck, and I feel very, very tight in the neck and shoulders.
"I tried to play on Wednesday and I am bitterly disappointed not to be going out.
"But after last year's experience of trying to play through an injury for one or two weeks, it ended up costing me six months away from the game."
Nick Faldo was the last British winner of the Masters in 1996 but Casey, speaking before making his decision to pull out of the Houston event, said: "I'm older, greyer, and feel like the next decade is my big opportunity."
He has four top-10 finishes to his name already this season and was runner-up to Ian Poulter in the World Golf Championship Match Play event.
Casey has also had four top-20 finishes at Augusta - he was 20th last year, to follow 10th and 11th places in 2007 and 2008 respectively, however his best finish came in 2004 when he was sixth.
"Augusta just suits my game and although my debut remains my best there, I'm maturing as a golfer and a person every year," he said.
However, he admitted his preparations last year were affected by his victory in Houston.
"It was a long tournament last year with all the rain delays that we had and I think emotionally it took a little bit out of me," said the Phoenix-based Englishman.
"If you don't have everything in place going into a major then you're going to be found out and I think that showed where I finished at Augusta the following week.
"If you look at results after winning tournaments in Europe I have struggled slightly the following week, winning in Abu Dhabi and missing the cut a couple of times in Qatar."
Two-time Masters champion Phil Mickelson and 50-year-old Fred Couples, who won his third event of the season on the Champions Tour last weekend, feature at the Redstone Golf Club this week.
US-based Englishmen Luke Donald and Greg Owen are in the field, along with England's world number four Lee Westwood, Northern Ireland's Rory McIlroy, Ireland's Padraig Harrington, Scotsman Martin Laird and highly rated German Martin Kaymer.
World number six Ernie Els, winner of the last two tournaments on the US Tour and seeking his first Green Jacket at Augusta, is also in the high-quality Houston line-up.