The look on Lauren Alaina's face when she joined Martina McBride onstage for "This One's for the Girls" captured the true spirit of CMT's Next Women of Country Tour.

It happened late into McBride's Saturday night (Feb. 11) headlining concert at Nashville's Ryman Auditorium. Not only was it Alaina's first time to perform on the historic stage, she was clearly having the time of her life as she swapped vocal lines with one of her musical heroes.

Given the strength of McBride's voice throughout the 22-song set, it's almost hard to imagine that it's been almost 25 years since she released her debut album, The Time Has Come. What's undeniable, however, is the string of hits and memorable album tracks she has created through the years.

In any case, spending time on the road with McBride can only be a learning experience for Alaina and the new country trio Post Monroe, who opened the Ryman concert.

The Next Women of Country Tour is part of McBride's larger Love Unleashed Tour, an endeavor she says is aimed at cultivating a "circle of love and positivity" at each show. Backed by an expert six-piece band, McBride also offered a lesson in creating a well-timed set list that managed to balance upbeat material with the more serious songs that are a cornerstone of her song catalog.

After opening her set with "Love's the Only House" and "My Baby Loves Me," McBride said she was in good spirits because the Ryman is her favorite venue to play and that she veered away from social media leading up to show time.

"I'm in a really good mood," she said. "I didn't get on Facebook today. It makes a real difference. Try it sometime."

She played the mega-hits, including "Blessed," "Wild Angels," "Safe in the Arms of Love," along with "Diamond" and other songs from her latest album, Reckless. And, of course, there were powerhouse versions of "A Broken Wing" and "Independence Day." She also performed two classic country tracks from her Timeless album -- Merle Haggard's "Today I Started Loving You Again" and Lynn Anderson's "Rose Garden."

McBride's fan base remains strong and constant, so Alaina is likely to be the biggest beneficiary of the current tour. Her just-released album, Road Less Traveled, is already generating sales and critical acclaim, and the tour is just another piece of Alaina's reintroduction at age 22 after dealing with an eating disorder and her parents' divorce.

Those who remember Alaina as a 15-year-old competing on American Idol will be impressed with her current comfort level onstage and, above all, her voice. After undergoing vocal cord surgery in 2014, her voice really is stronger than ever.

Her vocal power is effortless, yet she understands the importance of nuance even as she sang against the volume of a three-piece band through material on the new album, including "Doin' Fine," "My Kinda People" and the emotionally-charged "Three."

Post Monroe has the potential to expand its audience after last year's introduction with "Red Hot American Summer." The vocal harmonies of Ashlee Hewitt, Whitney Duncan and Shelby McLeod were stunning at Saturday's show -- no mean feat for a new trio performing at one of country music's most prestigious venues.