Day 3 (June 18) of Country Jam 2016 was a big one — and that's really an understatement. Although fans had to battle some serious heat throughout most of the day, the payoff was well worth it.

Saturday night's headliner, Blake Shelton, was celebrating his 40th birthday, and although the Country Jam crowd made sure to sing him a round or two of "Happy Birthday," it was Shelton who had the birthday surprise for fans. Near the end of his set, after playing well past his scheduled show end time, Shelton brought out girlfriend Gwen Stefani to perform their duet "Go Ahead and Break My Heart" ... and the crowd went wild. That wasn't all, though: Stefani came back out to sing "Hella Good," a song by her band No Doubt an unexpected twist, but a totally awesome one.

Other acts to take the stage on Saturday included Annie Bosko, High Valley, Darryl Worley and Big & Rich. Side stage acts included Dylan Jakobsen, Bosko, Adley Stump and Lauren Ashley & the Trainwreckers. Flip through the photo gallery above to check out some of the 10 best shots from throughout Day 3 of Country Jam 2016; the festival concludes on Sunday (June 19).

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