Carrie Underwood and Miranda Lambert at the CMT Music Awards on June 4. Credit: Michael Loccisano/Getty Images

Besties! Carrie Underwood and a recently slimmed down Miranda Lambert posed together while arriving at the 2014 CMT Music Awards, before they were set to hit the stage to perform their new duet "Something Bad" on Wednesday, June 4.

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Underwood donned a long, floor-length gown with a keyhole cutout. The American Idol alum paired her printed dress with drop earrings and an embellished clutch.

Lambert, who a source tells Us Weekly in this week's cover story is "extremely confident" since dropping 45 pounds, showed of her new slim waist in a belted, beaded mini dress. Blake Shelton's wife opted to wear her hair up which showed off her trim figure even more.

 

The five-time Academy of County Music female vocalist of the year winner "feels she's at her best," another source tells Us. To slim down, Lambert started changing her diet and focusing on eating more protein-packed foods like chicken breasts and broccoli.

"There was no miracle," she has said. "I'm just not a glutton anymore. I'm not eating fried chicken for lunch and then fried chicken for dinner too. I got to draw the line at some point."

For more details on how Lambert slimmed down, pick up this week's issue of Us Weekly.