When he was on the cusp of his major victory at Southern Hills 30 years ago, you see, a life really did hang in the balance.
His caddie, Shayne Grier, knew there was something wrong after Green snap-hooked his tee shot on the 15th hole in the final round of the 1977 U.S. Open on a steamy Sunday afternoon in Tulsa.
'He handed me the club and said, `Stay away from me and meet me at the ball,'' Grier recalled.
It seemed strange coming from a player who chatted and joked with his caddie all the time.
What Grier didn't know on that 15th tee box was that there had been a threat on Green's life. Police pulled Green aside before No. 15 and told him a woman had called and said someone was going to shoot him when he reached the 15th green.
'We had three options,' Green said recently. 'We could stop play, clear the course, I could play without a gallery. They could stop play and we come out the next day and finish up ... or we could continue play. I said, `Let's play. I can't be more nervous than I am right now. Let's get it over with.''
Police in pith helmets and riot gear walked down the fairways with Green the rest of the day, their hands resting on their guns. They asked the TV cameras covering the event to pan the crowd, hoping they'd find the sniper.
Green got a break despite his bad shot off the tee on No. 15. It hit a tree, bounced into the rough and left him with a clear shot to the green. He hit an 8-iron to about 30 feet from the hole.
Green told Grier to stay away from him while he was lining up his putt, but again, didn't tell him why.
'I got over the putt, I'm thinking, `Am I supposed to be shot?'' Green said, recalling the emotion on 15.
He saved par there and it was a strange sight. Only Green, Grier -- who was holding the flag -- and Frank Tatum, chairman of the USGA competition committee, were standing on the green. There were no scorers, no cameramen, no standard-bearers. Andy Bean, who was in the twosome with Green, had also been told to stand clear.
After spraying another shot right from the 16th tee box, Green told Grier of the dire situation. Again he asked Grier to stay away, trying to keep his caddie out of harm's way.
'I said, `Hey, Hubert, I grew up in the streets in Worcester, Massachusetts. If someone's going to hit me, they weren't going to give me a telegram. Let's just give them a bigger target to shoot at.''
Walking alongside his caddie again, Green hit his approach to about 4 feet and made birdie.
'I figured me telling him that might have broken the ice,' Grier said. 'He hit it stiff.
'I thought that was one of my better caddying jobs, to be honest.'
Today, a death threat against one of the best players during the final round of a major would dominate the news if it ever became public. Back then, Green did talked to Jim McKay of ABC Sports about what had happened.
But it was an understated interview.
Green simply wanted the whole thing to go away.
'Afterward when we were in the locker room, it was just Hubert and I,' Grier said. 'Hubert looked me straight in the eye and said, `Shayne, don't talk about this. It's not good for golf. We don't want other kooks coming out and doing that.' It showed what Hubert was made of.'
No arrests were made, and Green never followed up on the incident.
In the 30 years since that historic and harrowing day, Green has talked very little about it, saying he never really thought it was worth discussing.
He has broken his silence of late, in an interview two years ago with Golf Digest magazine, earlier this year with Golf World magazine, and also during interviews at his Hall of Fame induction ceremony in April.
His final putt on No. 18 was to win the tournament and avoid a playoff with Lou Graham, which would have meant another 18 holes Monday. He hit a tricky 4-footer that went in.
'I two-putted, won the tournament. I remember saying `Chicken.' I didn't say it loud,' Green said.
Green won 19 times and two majors, the other a victory at the 1985 PGA Championship at Cherry Hills.
In 2003, he was diagnosed with oral cancer -- another very real death threat. Chemotherapy and radiation beat that cancer, though Green, 60, is still weak. He can't eat much solid food and his voice changes a lot.
But he remains upbeat. He is, after all, still alive.
'I know what I remember him for,' said Curtis Strange, who was inducted into the Hall of Fame in the same class as Green. 'Tenacity, overachiever in a very, very positive way, and quite frankly, winning the Open under difficult circumstances on Sunday afternoon. I don't think there's many people that could have done that. He was just daring the guy.'