Alan Jackson seems to be pretty thankful that Zac Brown Band asked him to sing on the No.1 single 'As She's Walking Away,' as Jackson showed up to the band's Wednesday night concert at the Bridgestone Arena in Nashville with a 1966 Cadillac El Dorado convertible for Brown.

"That's Alan's car. It's gotta be. That's bada--," Brown tells USA Today, once he noticed the car. "Then Alan said, 'That's your car.' Man, that's unbelievable – it's unreal."

'As She's Walking Away' is the debut single from Zac Brown Band's second major label album, 'You Get What You Give.' The single shot up to the top of the country charts for two weeks, grabbing the attention of Grammy elites, who have nominated Brown and Jackson for Best Country Collaboration With Vocals.

"He was nice to include me on that," Jackson tells USA Today. "He's a pretty good fellow, and I just wanted to do something for him."

Jackson joined the band onstage that night specifically to sing the tune. Zac Brown Band end their 2010 tour this Friday on New Year's Eve with a hometown show at Atlanta, Ga.'s Philips Arena.