Trae Patton/NBC/NBCU Photo Bank via Getty Gwen Stefani and Blake Shelton
While performing a selection of some of his biggest hits, Shelton also partook in a solo rendition of his popular duet "Nobody But You," which features wife Stefani, 52.
Standing before the packed crowd at the show, Shelton performed his lines of the song in person, while a video of Stefani played behind him, singing her parts of the romantic duet.
An insider at the event tells PEOPLE that "the entire performance was so heartfelt" and Shelton even put his hand on his chest as he walked towards the screen that featured Stefani, where he blew her a kiss.
"Nobody But You" was previously released in January 2020 and marked Shelton and Stefani's third collaboration together following 2016's "Go Ahead and Break My Heart" and 2017's "You Make It Feel Like Christmas" (The pair also released their collaborative tune "Happy Anywhere" months later in July 2020).
At the time they released "Nobody But You," the pair also shared a music video for the song, which features several clips of the couple singing while cuddled up on the couch with their dog Betty. Some of the footage even appears to be self-shot moments from their day-to-day life — including a compilation of sweet selfies with a make-up free Stefani laughing as Shelton showers her in kisses.
Elsewhere that same month, Shelton and Stefani also performed the track during the 2020 Grammy Awards. There, Shelton took the stage first, singing solo with a guitar in hand before Stefani joined him midway through.
Mohegan Sun's 25th anniversary event will continue Saturday evening with a concert from Harry Styles as well as a star-studded red carpet.