It's been three days since Miranda Lambert and Blake Shelton announced that they would be divorcing after four years of marriage. Despite this being an extremely tough time in both of their lives, Lambert was all smiles as she took the stage for a surprise performance in Tennessee.

The 31-year-old country singer got on stage at The Basement in East Nashville on Wednesday during her best friend Ashley Monroe's show and showed no signs of sadness as she sang her song "Heart Like Mine," according to People. Lambert stunned in a black dress and studded boots, sporting a huge smile. 

"It was so cool," concertgoer Randal Peterson told Us Weekly. "Sam Palladio, Phillip Sweet and Meghan Linsey were all there for the show, and Miranda came out during Ashley's encore."

"They killed it," Peterson added. "The whole audience was silent and really focused when Miranda started singing."

Lambert did get a little emotional at one point when she first started singing, but she "looked over at Ashley and they both smiled," Peterson said, adding how gorgeous Lambert looked.

It's great to see Lambert smiling during her first stage performance since the split because just a few days before the divorce went public, this wasn't necessarily the case. Lambert completely broke down in tears on Saturday night during her concert in Wyoming. It was a very emotional performance, as she sang just the first verse of her hit song "The House That Built Me" through tears.