As Keith Urban prepares to become a member of the Grand Ole Opry tomorrow night (April 21), it's odd to think that just two weeks ago he had no idea this would be happening. The Aussie received the "shocking" invitation during the April 10 All for the Hall benefit concert in Nashville.

Keeping the secret of the Opry invitation from Keith was a tough one, especially when it came to making sure he didn't schedule anything on his intended induction day. His wife, Nicole Kidman, had a plan, though. She penciled in a friend's birthday party on their calendar.

"That's all I knew, that it was a friend of my wife's birthday written on the schedule," Keith says, "which apparently is totally fictitious, but I didn't question it. I was just gonna go."

To put things into perspective, Keith recalls the first time he stepped on that legendary stage, and how he got to meet one of his musical heroes backstage. "I was such a Ricky Skaggs fan," Keith recalls. "I remember that he was so approachable, and I was like 'I can't believe I'm talking to Ricky Skaggs.' But that's what it was like behind the scenes at the Opry -- everyone was approachable and so laid back."

When Opry member Vince Gill, along with Rascal Flatts and Diamond Rio, presented the "For You" singer with the honor, he was overcome with emotion. "I was thinking what it means to me to be inducted into the Opry is probably no more than a feeling of they know where my heart is," he explains. "My whole childhood was predominantly immersed in traveling around to country festivals and performing and competing in these talent quests."

Even though Keith's heart has always been focused on country music, he does recall a time -- around the age of 15 -- when he had to step outside of his comfort zone. "I was in this heavy metal band for like two weeks, and I got fired for playing these chicken-picking guitar solos, because it was a band that played all this Judas Priest and Whitesnake songs," he remembers. "I was totally immersed in Ricky Skaggs at the time. I had bought Highways and Heartaches, and I just discovered [guitarist] Ray Flack and I'm like, 'This is fantastic.' That, to me, sums up what my conundrum was at the time; the question of, 'Well, what do I do? What sort of music should I be making?' The foundation was always country, so to get this induction ... this is exactly where my heart is, where it always has been."

Fans who won't make it to Nashville tomorrow can watch Keith's induction on GAC's "Noteworthy at the Opry," which airs live April 21 at 9PM ET.