He was checking up on his U.S. team at the Presidents Cup when he noticed Steve Stricker in a bunker at Royal Montreal, getting advice from assistant captain Jeff Sluman. It wasn't long before Nicklaus joined them.
The last competitive shot he struck was two years ago at St. Andrews, when he holed a 15-foot birdie putt for a 72 in the British Open. So ended the career of golf's greatest champion, and he ended his retirement season on an even greater note when the Americans delivered a victory for Captain Jack in the Presidents Cup.
So it was strange to see him back as the captain, even with a mild protest from his wife.
'I was thinking, 'Oh my gosh, how can we top 2005?'' Barbara Nicklaus said from her hotel room in Montreal, where she was getting ready for yet another opening ceremony at the Presidents Cup.
Deep down, she knew the answer.
'He's got that little g-o-l-f thing,' Mrs. Nicklaus said with a laugh.
They have been together for nearly a half-century, married a month after Nicklaus nearly won the U.S. Open as a 20-year-old amateur. One of the legendary stories about their honeymoon was Nicklaus playing Pine Valley, and his bride having to drive around the perimeter of the course because women were not allowed on the property.
She was there for his 18 professional majors that spanned 25 seasons, for his emotional retirement at the home of golf. She has noticed the ease with which he has resisted temptation to play one more time at the Masters or his Memorial Tournament.
'He's not playing anymore, although he's as happy as can be,' she said. 'He's probably traveling more because he's got over 60 golf courses under construction. And he's loving it. That part of his life is fulfilled. The golf part of his life ... you never get rid of that.
'I don't think he misses playing,' she said. 'I know he misses the competition.'
Being captain of the Presidents Cup team helps fill that void.
Winning the cup never hurts.
'It keeps me involved in golf,' Nicklaus said after announcing his six foursome teams for the opening session Thursday. 'Being captain, I had to keep up with the game. Even though I don't play, I still want to be part of the game.'
This is the third time Nicklaus has been captain of the Presidents Cup, and the first time was a disaster. It was 1998 at Royal Melbourne in Australia, matches played close to the holidays and absence of any measurable interest by the players. They suffered the worst defeat in U.S. team history, 20 1/2 -11 1/2 , and players later told Nicklaus they let him down.
The respect was shown in 2003 in South Africa, amid concern that some players might not want to travel halfway around the world the week before Thanksgiving. They staged a strong rally on the final day to forge a tie.
Then came 2005 in Virginia, where the bond between a 67-year-old icon and a dozen players was never stronger. The year began with tragedy for Nicklaus when his 17-month-old grandson, Jake Walter, drowned in a hot tub. On the eve of the final round, players presented Nicklaus an oil painting of Jake and his curly blond locks, and tears flowed from all corners.
'It's hanging in our front hall,' Mrs. Nicklaus said. 'Every time we pass it we not only think of our Jake, we think of the team, and how precious they were to even think to do something like that.'
Perhaps the most grateful of his decision to return are the 12 guys playing for him at Royal Montreal.
Nicklaus is a hands-off captain who lets his players be themselves and enjoy themselves. He has them write down their choices of partners, even those with whom they don't want to play, and matches them accordingly.
He brings experience and mystique, and just the name 'Nicklaus' inspires.
'When he does speak, everyone listens because obviously he's the greatest player of all time,' Tiger Woods said. 'You always want to hear what he's going to say.'
Well, not always.
Nicklaus is quick with the needle, even with his own team. Charles Howell III shared the story this week about the first team meeting outside Boston last month, when Captain Jack congratulated Zach Johnson, David Toms, Hunter Mahan, and was making his way around the room when he came to Howell, who had not finished in the top 10 since March.
'Charles,' he told him, 'you need a lesson.'
During a conference call last month to discuss his team, Nicklaus referred to a strange incident years ago when Woody Austin walked off the green banging his putter against his head until it broke.
'I don't know whether Woody will bring golf or bang himself in the head,' Nicklaus said.
It's all in good fun, although Nicklaus says he can be a little quick with the tease. It's all part of the package, part of why the Americans appear to be so much more relaxed at the Presidents Cup than they are in the Ryder Cup.
And maybe that explains why they have not lost the Presidents Cup since 1998 in Australia.
It begins Thursday at Royal Montreal, the oldest golf club in North America, when Stricker and Mahan play in the first alternate-shot match against Adam Scott and Geoff Ogilvy.
The Americans are in better form. The International team has a stronger collection of players.
The intangible, again, could be Captain Jack.