Phil Mickelson late WD at Torrey

SAN DIEGO -- Phil Mickelson's back again gave him problems on Friday, leading to his withdrawal from the Farmers Insurance Open hours after his second round concluded.

Mickelson's publicist, T.R. Reinman, confirmed the news late Friday night. He's expected to visit with doctors to determine a course of action in the coming days.

Mickelson, 43, a three-time winner of his hometown event, got treatment after Thursday's round and again Friday morning. He still managed to shoot a 1-over 73 on the South Course to complete 36 holes at 2-under 142 and in a tie for 32nd place.

But after the round -- and before he decided to withdraw -- he clearly tried to take a big-picture view of his situation.

"I have the entire year, I've got majors coming up, I've got other tournaments coming up and I don't want to get into bad habits,'' Mickelson said. "My game is pretty sharp getting ready to start the year, and I could tell I'm making terrible swings out there relative to the way I've been swinging.

"I love this tournament and I want to play here. I love playing in San Diego, and this is a place where I grew up playing, so I really want to play. And part of me also says that I'm getting in bad habits, and if I hit it in this rough here, I've really got an issue because I've got to swing awfully hard to get it out and it jars it. So I'm a little torn right now on the best plan of action.''

Prior to Thursday, Mickelson said there had been no physical issues. But in the first round, he said the back "locked up'' and that "it's just tight and I just couldn't swing from the top."

Last week, he tied for second at the European Tour event in Abu Dhabi, United Arab Emirates, and was making his 2014 debut on the PGA Tour here.

Mickelson is to defend his title next week in the Phoenix Open. After Phoenix, he is scheduled to play at the AT&T Pebble Beach National Pro-Am the following week. Mickelson is not planning to play at Riviera or Match Play because his children have spring break at two schools.

Information from The Associated Press was used in this report.