I held my breath as Phil Mickelson’s putt tracked toward immortality. I was milliseconds away from witnessing history.

59.

The rarest pinnacle in professional golf — its Holy Grail, if you will.

So rare that it’s only happened five times in PGA history — and not by names you would expect.

A quick rundown of some of the PGA’s most celebrated players includes Sam Snead, Jack Nicklaus, Tiger Woods, Byron Nelson, Ben Hogan, Arnold Palmer.

None of those guys have written 59 on their scorecard following a PGA round.

The “59 Club,” as they are called, only features five men: Stuart Appleby, Paul Goydos, David Duval, Chip Beck and Al Geiberger.

Kind of like the Perfection Club in the NFL of which only the 1972 Miami Dolphins are members.

And now Phil was about to join.

It was the first round of the Waste Management Phoenix Open from TPC Scottsdale in Arizona. The Golf Channel was supposed to begin coverage of the event at 3 p.m., but Mickelson’s rush to golfing greatness prompted producers to start things up a little earlier.

He left a birdie putt short on his 17th hole, which would’ve already put Mickelson on pace for the coveted 59 number with one hole to play.

So that left one more chance. Phil teed off on No. 10, so he would have to accomplish this rare feat on the par-4 No. 9, a hole he’d birdied only once in his past 20 rounds at TPC Scottsdale.

A good tee shot and solid approach left Mickelson a long putt, but still a makeable one.

When he started it rolling toward the hole, it looked dead center.

I couldn’t believe it.

A Thursday afternoon before heading to work and I’d stumbled onto history.

This is what baseball fans must feel like when they switched over to the Chicago White Sox game at Seattle last year. Probably not fans of either team, but a relatively unknown pitcher named Phillip Humber was one inning away from throwing a perfect game — baseball’s version of the Holy Grail.

Humber did it and now it seemed Mickelson was about to do the same.

Only it didn’t happen.

The ball raced toward the hole and, at the last minute, seemed to change its mind. Instead of dropping in, it skirted around the edge of the cup in a near perfect circle and stayed out.

Mickelson had still shot an opening-round 60 and tied the course record to sit in a commanding lead. Not too shabby, but to hear Lefty’s comments were like he’d just lost the golf tournament.

“I’m kind of mortified that didn’t go in,” Mickelson told the Golf Channel afterward. “You just don’t get those chances very often.”

Mickelson finished with 11 birdies in his round — just a few days after he’d labored to make the cut at Torrey Pines.

But here’s a thought.

Of the five guys in the “59 Club,” only Duval went on to win more than one PGA tournament for the remainder of their careers. Duval won four more times, highlighted by the British Open before he completely fell off the map.

The last two players to shoot 59 — Goydos and Appleby in 2010 — Goydos didn’t even win the tournament he carded that score (2010 John Deer Classic), while Appleby’s 59 gave him a victory at the 2010 Greenbrier Classic, but nothing since.

As for the Miami Dolphins: that franchise won one more Super Bowl the following year in 1973, but nothing else since.

For a guy still focused on winning majors, maybe it’s a good thing for Phil that his putt did not go in.