Three-time Masters champion Phil Mickelson has ruled out playing practice rounds Monday and Tuesday after withdrawing with a back injury after 10 holes in the third round of the Valero Texas Open.

Phil Mickelson in action during the third round of the 2014 Valero Texas Open.

Mickelson was one over par at the time and four over par for the event when he advised his playing partners Stuart Appleby and John Merrick he could no longer continue in the $US 6.2m event.

“My back’s feeling great, my body’s been feeling great,” he said.

“I felt as good as I have all year.  My speed is back, I was hitting the ball hard, driving it great.  I pulled a muscle on my downswing trying to hit the ball hard on the second hole (his 11th).

“It just killed me and it wouldn’t subside for about 10 to 12 seconds.

“I’m going to go back to San Diego for a couple of days and have a doctor take a look at it but there’s really not much you can do for a pulled muscle.  I hope to be okay to play in the Shell Houston Open but I just don’t know.”

Mickelson was competing in San Antonio for a first time since 1992 and in what was his rookie season.

After making the halfway cut in sensational manner on Friday night he had promised to take his daughter to tonight’s (SAT) San Antonio Spurs versus the New Orleans Pelican NBL game here in San Antonio.

Australia’s Stuart Appleby played the first two rounds alongside Mickelson and despite three-putting the last hole in a round of 74 to miss the third round cut, he gave further light on Mickelson’s withdrawal.

“He had hit a few poor shots but it was the first hole of our back nine when I really noticed there was something wrong, as he just didn’t look right,” said Appleby.

“Then he sort of feathered one down the next and that was it.

“He then came over to John (Merrick) and myself and said:  “Look guys.  I think something’s going on in my back and I’m out of here.

“He had been saying his back was fine but then we’re all getting to that age when these things start happening in our bodies.”