The No Doubt frontwoman and country singer Blake are due to perform their new duet, Go Ahead and Break My Heart, at Sunday night's (22May16) ceremony, and Gwen has been documenting their trip to Sin City on social media.

The blonde beauty shared a number of photos of her man gearing up for the big gig, starting with video footage of Blake singing on a plane as they headed to Vegas on Friday (20May16).

She then posted images and clips of Blake in rehearsals on Snapchat on Saturday (21May16), and even found time to goof around as she photobombed a picture her brother Todd had tried to take with Blake, with Gwen popping her head in between the pair in the background.

"@blakeshelton @toddboy01 selfie w (with) Blake Gx," she simply captioned the post.

The singers also enjoyed a little golfing session with Todd at the new Top Golf Las Vegas venue, where Gwen shared a funny shot of Blake puckering up to kiss her brother on the cheek.

The new couple, which met while serving as mentors on U.S. talent show The Voice, hasn't been shy about expressing its love for one another on social media since going public with its romance in November (15), just months after Blake divorced Miranda Lambert and Gwen split from husband Gavin Rossdale.

Blake recently revealed they tried to keep their blossoming relationship under wraps at first, but it quickly became harder and harder to hide their feelings for each another.

"At the time, when you go through what I went through with my divorce, you never know when it's the right time to step out and say I've started seeing someone," he explained to Country Countdown USA. "But what I found out, because it wasn't someone from my hometown, it was Gwen Stefani that I was beginning to have this relationship with. There was no hiding it. If I glance her way, it's the cover of magazines. If I could have kept my personal life private, I would have. Since I can't, I might as well let people in on the truth."

Blake also admitted the couple's "trust issues" from the breakdown of its respective marriages actually helped them bond and write Go Ahead and Break My Heart.

"Of all the people, she was the last person I expected to step out of the crowd and be the one to have my back, and be there and be the shoulder and be the one to fight that fight with me, getting back on my feet, and out of nowhere, there she was," he gushed.

However Blake admits he almost ended up in the dog house with his 46-year-old girlfriend after failing to realise just how many hit songs she has had.

"One day I was driving down the road and The Sweet Escape came on and Gwen was in the car with me and the intro started and I was like, 'What is this? I know this song. I love this song,'" he recalled with a laugh, "and she said, 'That's... that's my song!'"