SOUTHAMPTON, N.Y. — Phil Mickelson is running out of time.

Mickelson doesn’t need to be reminded that this is his 27th appearance in the U.S. Open, more than any of the 156 players at Shinnecock Hills. He wouldn’t want to be reminded that 65 players — including the last four major champions — were not even born when Mickelson was low amateur in his first U.S. Open in 1990 at Medinah.

“I just can’t believe that time has flown by so fast,” he said Monday.

The desire hasn’t changed, only the emphasis.

Mickelson didn’t win a major until he was 33 and in his 12th full year on the PGA Tour. Back then, any major would have sufficed. A year after he won the 2004 Masters, he added a PGA Championship. And then in 2013 at Muirfield, he surprised even himself by capturing the British Open.

One to go for the career Grand Slam, the one that has vexed him the most.

He has more runner-up finishes in the U.S. Open than the other three majors combined. So when Mickelson was asked if he had unfinished business at Shinnecock Hills, he paused briefly before delivering an obvious answer.

“I can say that a few times in this tournament,” he said.

It helps that Mickelson has a strong history at Shinnecock Hills, which he refers to as one of his favorite courses.