( CNN ) -- His old rival Tiger Woods is missing the Masters , but three-time champion Phil Mickelson should be teeing off at Augusta next week after allaying fears about his fitness . The veteran golfer pulled out during last week 's Texas Open with a muscle problem , having missed the Farmers Insurance Open in late January with a back issue . However , the 43-year-old raised hopes of claiming a career sixth major title after coming through Thursday 's opening round at the Houston Open in good shape . `` I feel a lot better , '' Mickelson told the PGA Tour website . `` I travel with a light therapy machine , and I got on it right away , and I think that made a world of difference as far as expediting the healing process to where it does n't hurt anymore . `` It just feels sore like I was working out , as opposed to kind of a painful experience . '' Mickelson , the 2011 Houston winner , carded a bogey-free four-under-par 68 to be tied for 18th in a group including fellow veterans Ernie Els , Davis Love , Retief Goosen and 2012 U.S. Open champion Webb Simpson . They were three shots behind leaders Bill Haas -- the PGA Tour 's 2011 FedEx Cup champion -- and fellow American Charley Hoffman , seeking his first victory since 2010 . World No . 7 Rory McIlroy , another Masters title contender , was tied for 59th after a 70 . On Tuesday and Wednesday , fifth-ranked Mickelson spent time practicing at Augusta , where he wore the victor 's fabled Green Jacket in 2004 , 2006 and 2010 . `` I was able to spend more time with short irons , chipping , putting as opposed to driving the ball , but even that was pretty good today , '' he said . `` I hit the ball well off the tee and did n't miss very many fairways . ''
Phil Mickelson raises hopes of a fourth Green Jacket after returning from injury . American four shots off the lead after opening round of Houston Open . He practiced at Augusta earlier this week ahead of season 's opening major .