During a Sept. 16 concert in the Canadian city of Edmonton, country star Keith Urban spontaneously selected two young sisters from the audience to visit him onstage. He had no idea how the encounter with 14-year-old Hailey Benedict and her younger sister Makenna would play out.

“The typical questions are, ‘Where are you from? Who are you here with tonight?’” Urban said this week from his home in Nashville, explaining how his onstage conversations with fans generally unfold. “Typically you round it up with, ‘Let’s take a selfie.’"

But neither of the Benedict sisters had a cell phone. With nearly 20,000 people watching inside the new Rogers Place arena, Urban stood on the brink of a momentum-killing, dead end moment.

“What do I now? It just felt so awkward. Out of the blue, I said, ‘What do you want to do? What’s the dream job?’”

To his immense relief, Hailey replied that she aspired to be a singer-songwriter.

"When she said ‘singer-songwriter,’" Urban recounted, "I was just like, ‘Thank you, God! Thank you! I can work with this.’ And it all just flowed from there.”

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Urban invited Hailey to sing one of her songs. He got her a stool and a guitar. His paternal instincts kicked in — he has two young daughters with his wife, actress Nicole Kidman — as he adjusted the guitar to Hailey's satisfaction. She sang and strummed with impressive confidence.

The audience went crazy. A video of the utterly charming encounter posted to Urban's Facebook page amassed more than 2.5 million views and 17,000 shares in less than a week.

“What are the odds that that’s what she’d want to do?” he said of Hailey's career choice. “If she had been like, ‘I want to be an accountant,’ it would have been, ‘Cool. OK, bye!’”

Most arena concerts are meticulously scripted, right down to the between-song banter. Even Urban, one of the most skilled guitarists in Nashville, works from the same set list every night.

But his concert ritual of inviting fans onstage supplies the seat-of-his-pants spontaneity he craves. He thrives on the challenge of making moments on the fly, as will be evident when his RipCord World Tour stops at the Smoothie King Center in New Orleans on Oct. 15.

“I love the spontaneity so much because it’s the most real thing that’s going to happen,” he said. “I’m willing for it to be a disaster because the payoff, if it isn’t a disaster, is a really great moment.

“Not a single thing I do when I pull someone onstage is ever scripted. It breaks my heart when I’ve heard people think that I’ve staged somebody in the audience or hand-picked somebody (in advance). It’s nonsense. Everything in my world is completely spontaneous and random, and anybody that works with me knows that.”

The craving for the adrenaline rush of spontaneity, he believes, is a vestige of the years he spent performing in rough-and-tumble clubs in his native Australia.

“Someone could get up onstage and either sing or want to clobber the bass player. It’s all teetering on the edge of something. I find that energy just really magnificent to be in the middle of. It’s coming more from the punk world than anything else, but that’s very much the Aussie club world that I come from.”

In a throwback to those days, he likes giving fans a chance to get up close and personal during his nightly forays into the audience. Before concerts, his security personnel ask the venue’s security team to exercise restraint.

“They’re always told that when we come out through the crowd, don’t do the whole linking-arms, keeping-the-crowd-back crap. Get out of the way and let us try and see if we can get through the crowd our way, 'cause it’s much more exciting.

“It’s fraught with 'anything could happen.' Someone can grab your hair or put you in an overly passionate hug that becomes a headlock. But it’s real, and the energy is so real. When everybody’s neatly parted like the waters, it’s so boring. I just find it lame. I’d rather have a little bit of chaos.”

There are real hazards to close quarters interactions with sometimes overzealous fans. More than once, he’s ended up with claw marks across his chest. “Thankfully, I have a wife that knows what I do for a living,” he said.

He even tries to maintain some degree of freedom on TV shows, which, due to the logistics of camera angles and timing, must be mostly mapped out in advance.

“At TV events, they’re like, ‘Are you going to jump off the stage?’ I don’t know. ‘If you do, which side would you jump off?' I’m not going to tell you, because I have no clue.

“Is this going to be spontaneous or not? The whole ‘rehearsed spontaneity’ is a little bit bulls---. I’d much rather be legit and real and suffer the consequences afterward.”

When such moments go right, they go right in a big way. The night after Hailey Benedict’s star turn in Edmonton, Urban facilitated a marriage proposal onstage in Saskatoon. He spotted a man near the stage holding up a sign behind his girlfriend that indicated he wanted to propose to her.

“I’m reticent to choose those signs, because then it starts a never-ending avalanche," Urban said. "Before you know it, you have it at every single concert.

“There was a plethora of other signs around, and I was about to choose another one. But everyone down in the front was screaming at me to keep looking at that guy’s sign. So the mob dictated that I chose that one that night.”

The couple, Ashley and Jacob, got onstage. Urban made Jacob get down on one knee to pop the question. Ashley said yes. Urban subsequently serenaded them with his ballad “Without You.”

The crowd, needless to say, ate it up.

“They were a great couple,” Urban said. “It worked out beautifully.”

Follow Keith Spera on Twitter, @KeithSpera.

Keith Spera writes about music, culture and his kids.