Jim "Bones" Mackay figured to be the one scrambling to make his opening start of the new year, not his longtime boss, Phil Mickelson.

But while Mackay has been itching to get inside the ropes, Mickelson took until the last minute -- in the wake of two sports hernia surgeries, the first of which was supposed to be routine -- before finally deciding that he will compete in this week's CareerBuilder Challenge.

On Oct. 19, just three days after tying for eighth at the Safeway Open, Mickelson had surgery that was supposed to keep him away from golf for just a month, with plenty of time to get ready for this week's event in La Quinta, California, where he is serving as the tournament's ambassador.

On the same day, Mackay, 51, who has caddied for Mickelson since 1992, had double knee replacement surgery. He chose to have both of his knees replaced at the same time in hopes that he'd be OK to resume work by this week.

"My knees hurt for years, especially last year," said Mackay, who has been on the bag for all but one of Mickelson's 42 career PGA Tour victories. "The weird thing was that ultimately when the doctor who agreed to do both knowing what I do and how important it was for me not to miss any work ... when I saw him the first time after the surgery, he said my knees were much worse than he expected. It was a disaster."

Dr. Ted Firestone performed the surgery near Mackay's Arizona home at North Scottsdale Hospital on the same day Mickelson had sports hernia surgery in California. It was a coincidence, as both had been planning for their procedures for months, with the golfer expecting to be back practicing by mid-November.

But Mickelson had issues that required a second sports hernia surgery on Dec. 12. He didn't get back to hitting balls until last week, hence his late decision to play. "I don't know where my game is," Mickelson said. "But I figure the only way to find out is to play."

Mickelson and Mackay were most recently seen on the course during tournament play in October at the Safeway Open, where Emiliano Grillo, right, was among Mickelson's partners. Eric Risberg/AP Photo

Mickelson, 46, is coming off a third consecutive winless season, but he had numerous close calls, including a runner-up finish to Henrik Stenson at The Open.

The relationship between Mickelson and Mackay is a unique one in golf in that it has lasted nearly 25 years.

But the rigors of walking courses and carrying a heavy golf bag finally caught up to Mackay's knees.

"I haven't been able to run for close to 10 years," he said. "Yeah, sure it hurt to work, but I got into a situation last year where I'd go home at night and they would throb so badly where it would keep me from falling asleep. At times it affected me 24 hours a day. I knew by Augusta last year that I had to do something pretty drastic. That's when I started to look into it."

Mackay said that after the surgery he needed to use a walker for a short time. He eventually moved on to a cane for a few weeks before being able to walk on his own. He played his first round of golf after seven weeks.

"It could not have gone any better," he said. "I would recommend that surgery to anyone who feels like they need it, because it is life changing. I've been walking miles at a time without pain for a number of weeks. It's been great. I had zero pain in my knees the entire time since the operation."

Mackay is a member at Whisper Rock -- where Mickelson designed both courses -- and said the surgery has made his knees better as it relates to golf. "I actually shot 70 the second round back," he said. "That's great for me."

Now comes the hard part -- walking all those golf holes while carrying a bag.