Like high schoolers earning college credits, the country music industry seems eager to fast-track rising stars into arena headliners.

Chris Stapleton graduated to arena headliner after his second album. Sam Hunt zoomed to the big marquee after just one album. And Thomas Rhett made his first Twin Cities headline appearance Wednesday at sold-out Xcel Energy Center to promote his third album.

There’s no question that after nine No. 1 country songs and three big-selling albums Rhett is popular. He drew 15,000 fans. The fledgling headliner, 27, praised the crowd for being the loudest one he’s ever heard and for turning a Wednesday night into a “Saturday night in the summertime.”

Well, I guess his idea of a Saturday night in the summertime is keeping it breezy, pleasant and innocuous.

Rhett lacks the moves and energy of Luke Bryan, the spirit and athleticism of Hunt, and the songs and gravitas of Stapleton.

The son of mid-1990s country star Rhett Akins, Rhett seems likable enough. He married his high school sweetheart (they met in first grade), and they adopted a girl from Uganda.

Many of his country hits have been about young love, which made the fans — about 70 percent of whom appeared to be teen- or 20-something women — swoon often on Wednesday.

Rhett’s songs are the most pop thing on country radio. The Georgia-born singer, with multicolored tennis shoes and a faux hawk ’do that he’s growing out, has no hint of an accent or pedal steel guitar. In fact, his band had a saxophone. Not that Rhett used it to great effect in concert.

Although he has a flair for the radio friendly, Rhett’s music is very diluted. Think Jason Mraz trying to be Justin Timberlake. Sample lyric from “Star of the Show”: “Oh, what gets me the most is you don’t even know / That you are, you are, you are the star of the show.” It’s not exactly “Say hey, good lookin’/what ya got cookin’? / How’s about cooking somethin’ up with me?” as Hank Williams sang.

Rhett was probably at his best when he and his five-man band ventured to a small stage at the back of the arena. “Sweetheart” was a doo-wop tinged slow dance from his new album, “Life Changes,” during which he danced with a woman born in 1943. “Marry Me,” his current single, was a clever ode to rejection, and “Round Here,” the hit Rhett co-wrote for Florida Georgia Line, proved his bona fides as a Nashville songwriter.

Despite his flair for radio hooks, probably the most interesting things Rhett played were a version of Bruno Mars’ high-energy, hip-hop-infused “24K Magic” and a sax-accented take on part of “Shout,” the old Isley Brothers classic.

Rhett even grafted Mars’ “That’s What I Like” onto the end of his own singalong hit “Unforgettable” — but the crowd sang louder to the Bruno tune. Go figure.

Opening was Old Dominion, a crowd-pleasing, good-time, harmony-loving group with pop smarts and a country ZIP code.