Three-time Masters winner Phil Mickelson has downgraded his injury concern from ‘painful’ to just ‘sore’ after posting an encouraging 68 on the opening day of the Shell Houston Open.

Mickelson has returned to competition after an oblique muscle injury in his back forced him out mid-way through the third round of last week’s Valero Texas Open.

Phil Michelson finds himself in media spotlight after shooting a first round 68.

And Mickelson arrived in Houston after playing 27 holes Tuesday and Wednesday at Augusta.

“I feel a lot better now five days later and the good thing is that I travel with a light therapy machine and I was working with it straight away on Saturday and that made a world of difference as far as expediting the healing process,” said the World No. 5.

“So coming off the course it doesn’t hurt any more only a little sore, as opposed to a painful experience.”

Not on bogey among the threesome of Phil Michelson, Keegan Bradley and Webb Simpson.

Mickelson contested the opening round of the $US 6.2m event alongside joint clubhouse leader Keegan Bradley who fired a 66.

And in a rare effort all three players in the grouping, including former US Open winning Webb Simpson, ended their rounds without a bogey posted among the trio.

“It’s a pretty cool thing for all three of us to go around bogey-free,” said Bradley.”We were walking up the last hole and Webb and Phil start yapping in our ear that none of us made any bogeys.

“Typical Phil stuff.”