Carolyn Dawn Johnson has played music in front of thousands of people before, but when she takes the stage Friday night at Mandalay Bay in Las Vegas, things will be a lot different.

Johnson is the opening act for the Girls' Night Out tour, the first all-female traveling country show. She's had modest success with two singles, "Georgia" and her current release, "Complicated," but her debut album, Room With a View, won't come out until August 7.

Still, Johnson feels the tour represents an opportunity to be a part of history. As backing vocalist and guitarist for Martina McBride, she has played major concerts before. Johnson was with McBride in 1999 when she played the Lilith Fair. Soon after, McBride began talking about doing a similar tour featuring women in country music.

"I remember talking about it on the bus," Johnson said. "I was always hoping that I could be a part of it when it did happen."

And now she is. As opening act, Johnson will be in front this time around. Inevitably, she will play to some empty seats as people file in to see the bigger names on the bill — Reba McEntire, McBride, Sara Evans and Jamie O'Neal.

She's counting on reaching those who arrive early, however. "I just hope ... I make an impact on them," she said. "I only get to sing three songs. To me, that's a big deal. I'm part of this. I think you can still make a difference in that amount of time."

Johnson, 30, picked up part of her work ethic growing up on a farm in Deadwood, Alberta. She polished her attitude watching McBride work night in and night out on tour.

"I always felt like she gave 150 percent every night," said Johnson, who slept on McBride's bus, in a bunk above her boss' children.

"That is something I want to be able to do. I feel like I do that. It didn't matter if she was extremely tired or very sick. She always gave all of that. I was amazed, standing back on that stage, seeing her perform like she does every night."

Already a successful songwriter — she co-wrote Chely Wright's #1 hit "Single White Female" and Jo Dee Messina's "Downtime" — Johnson hopes to follow McBride's example as a mother, someday building a family at the same time she builds a career.

"We kinda hung out every night when we got off the stage," Johnson recalled of the earlier tour. "I really got to get to know her and her family, which is a wonderful family. As a mentor in the music business and a mentor as having a family and being able to do all this, it's something I aspire to do, definitely."

But first, there's this matter of a tour. Girls' Night Out will benefit USA Harvest, a 14-year-old charity that donates millions of pounds of food annually to soup kitchens and missions across the country.

Anticipation is high. McEntire has just finished a five-month run on Broadway, where she starred in the smash "Annie Get Your Gun."

"I think it's going to be some good 'girl time,'" Johnson predicted. "We've talked about writing out there. We'll probably hang out a little bit, and Martina said something like she hopes we have a lot of fun backstage so it will translate out into the audience."