Backstreet Boys had an extra special guest in the audience of their Las Vegas residency show on Friday (Feb. 8): country megastar Shania Twain. She probably wasn't anticipating they'd personally serenade her, however.

Member AJ McLean — who also is pursuing a solo endeavor as a country music artist — pulled Twain on the stage with a red rose in hand, and she appeared to blush as the group sang their hit single "Shape of My Heart" directly to her, with McLean down on one knee with the rose to present her. Twain was singing along the entire time, knowing every lyric.

The unlikely collaboration has actually been a friendship spanning decades. In 1999, the country powerhouse and boy band teamed up for a televised performance of "From This Moment On," which was the first time they worked together.

Besides McLean going country, the band itself has other roots to country music, like when they famously collaborated with Florida Georgia Line on what became a No. 1 country single, "God, Your Mama and Me." The boyband's latest album, DNA, even includes a song that was co-written by country's Dustin Lynch.

The Backstreet Boys' Las Vegas residency, Larger Than Life, extends through Apr. 27 at Planet Hollywood's Zappos Theatre.

Non-Country Artists Who Unexpectedly Went Country