In one of the most memorable moments of the 49th annual ACM Awards, Merle Haggard was serenaded by George Strait and Miranda Lambert with Garth Brooks waiting in the wings.

Haggard was honored Sunday night (April 6) with the ACM Crystal Milestone Award to recognize his 50th year in country music. The living legend scored his first national Top 20 hit with "Sing a Sad Song" on Tally Records in 1964 and went on to accept 20 ACM awards over his career, including the first-ever ACM entertainer of the year award.

Stepping out first to introduce the tribute, Brooks remarked that Haggard had been a particular favorite of his father's and, as a result, one of his, as well.

"He had an unmistakable sound that was straight out of Bakersfield, Calif.," Brooks said. "You know I have to be talking about Merle Haggard, the recipient of tonight's Crystal Milestone Award.

"It's no news to anybody that Haggard has always been an outsider. He's a one-of-a-kind creative force that transcends any category, and the good times are not over at all. He's still making some of the most compelling music over his five-decade career."

Strait performed first, offering Haggard's first No. 1 single in 1966, "The Fugitive." He sang the tale of a man on the run -- though he'd rather not be -- in a smooth baritone reminiscent of Haggard's distinctive vocal style.

Following Strait, Lambert stepped to the front of the stage for "Tonight the Bottle Let Me Down," one of Haggard's best-loved honky-tonkers and a prime example of his gritty, working man's songwriting. That song was also released in 1966.

After the performances, Brooks called Haggard to the stage to accept his award, reminding everyone that Sunday was also Haggard's 77th birthday.

As Haggard made his way down the aisle, Brooks, Strait and Lambert led the whole audience in singing "Happy Birthday."

Once he arrived onstage, Haggard kept his remarks brief but gracious.

"Thank you very much," Haggard said, dressed in a classic black suit and hat. "I'm a little taller than this," he quipped, adjusting his microphone.

"Country music's been great to me all my life, and it's great again tonight. Thank you, everybody, for your participation in one of my most eventful evenings. This was a good evening. Thank you."