Phil Mickelson will skip Wednesday's pro-am for the Shell Houston Open, raising the possibility he will miss this week's PGA Tour event just days after withdrawing from the Texas Open with a pulled muscle in his right side.
"We haven't heard a word from Phil, so we don't know whether he's playing or not," a PGA Tour official told the AFP, according to the Golf Channel. "All we know at this stage is that we had a call saying he [needed to] be excused from competing in the pro-am."
Mickelson withdrew from the Texas Open after 10 holes in the third round Saturday. He was 4 over overall at the time.
"I pulled a muscle on my downswing trying to hit it hard on the first hole," Mickelson said in a statement Saturday. "It just killed and it wouldn't subside for 10 or 12 seconds.
"I'm going back to San Diego [for] a couple of days and have a doctor look at it, but there's really not much you can do for a pulled muscle. I hope I'll be OK to play the Shell in Houston, but I just don't know."
PGA Tour players are allowed to skip two pro-ams per season.
The injury also could jeopardize Mickelson's status for the Masters, with the year's first major set to begin next Thursday.
The Masters field already took a hit Wednesday when Tiger Woods withdrew after having back surgery earlier this week.