(REUTERS) - Phil Mickelson, who was recently diagnosed with locked facet joints in his lower back, said on Wednesday he will defend his title at this week's Phoenix Open.

The five-time Major champion had been in doubt with a back injury that prompted him to withdraw from last week's PGA Tour event at Torrey Pines in southern California after two rounds.

"I had a good practice session, though I didn't go full speed for much of it. I feel fine. I expect to play and play well," he said in a statement ahead of the Jan 30-Feb 2 Phoenix Open.

Mickelson, who was diagnosed with and treated for locked facet joints in his lower back, says he also plans to play next week's Pebble Beach National Pro-Am.

The 43-year-old Californian won last year's Phoenix Open at the TPC Scottsdale with a wire-to-wire victory that included an opening round 60.