Tim McGraw celebrated his upcoming Standing Room Only album with a secret show at famed West Hollywood venue Whisky a Go Go on Monday night (July 24.)

This was no ordinary show. Not only was it a pop-up event, but the country superstar held an unofficial meet-and-greet with fans standing in line to get in the doors, shaking hands and sharing hugs and high-fives before he headed inside to get ready for his set.

In video shared by TMZ, McGraw walked briskly across Sunset Boulevard towards Whisky a Go Go, surrounded by his security detail. He waved at those who honked and cheered in recognition of him, then went down the line of fans standing by the door, offering smiles and high-fives and posing for pictures.

Dressed in his stage clothes, McGraw was very recognizable: He wore his signature black cowboy hat, tight-fitting deep-vee shirt and jeans.

McGraw's Monday night set lasted upwards of an hour, and included both new material and road-tested hits like "Real Good Man" and "Something Like That." Fan-captured video from the show shows his rousing performance of "How Bad Do You Want It," the album-opening track off his 2004 project, Live Like You Were Dying.

According to TMZ, McGraw closed his set with "Hey Whiskey," a new track off Standing Room Only that the singer dropped earlier this summer. His pre-show Sunset Boulevard appearance wasn't the only special surprise the singer had in store that evening, either: He also brought pop singer-songwriter Richard Marx onstage for a duet rendition of Marx's 1987 hit, "Don't Mean Nothin'."

McGraw's Standing Room Only album is due out on Aug. 25.

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