In an upset not many expected, Thompson Square, the married duo made up of Shawna and Keifer Thompson, have won the Academy of Country Music’s Top Vocal Duo Award, besting odds-on favorite Sugarland, the winner in the category two of the last three years.

The announcement was made at the ACM’s Salute to the Military as part of the ACM Experience at Mandalay Bay Resort in Las Vegas.

"It’s very bittersweet," an emotional Shawna, whose father died last month, told the crowd, fighting back tears. “More sweet than bitter.

Kiefer was equally touched. "It's hard to talk when you're crying," he said after the couple embraced on stage.

The ACM Awards take place Sunday at 8 p.m. ET on CBS.