Carole King and James Taylor (Mohegan Sun)

As if the music industry wasn't already unpredictable enough, add this to the mix: one of the highest grossing tours this year will likely be by two singer-songwriters whose heydays were nearly 40 years ago.

While Carole King and James Taylor have remained popular since the early '70s, their current Troubadour Reunion tour has become the hot ticket of the summer, selling out arenas around the country. With tickets priced at upwards of $350 for some tour dates, they'll likely give Green Day, The Eagles, and Taylor Swift a run for the summer box office crown.

The duo performed two sold-out shows this week at the wonderful Mohegan Sun Arena in Uncasville, CT before heading to Boston this weekend.

At the Mohegan Sun show Sunday night, King and Taylor took the stage to perform a couple of songs together before being joined by the rest of their talented band.

Taylor kicked off the proceedings with the soft, pretty "Blossom," while King followed up with the simple ballad "So Far Away." Her husky voice has changed little in the past 40 years, and she looks great.

The other musicians joined Taylor and King for his country honky-tonk "Machine Gun Kelly," which was followed by the soaring ballad, "Carolina in my Mind."

Usually when men and women duet, it's the women who have the smooth, sweet sound and the men provide the rougher, edgier vocals. During this concert, the dynamic was reversed: Taylor was the oil, and King the feisty vinegar.

This was evident on her upbeat 1970s pop hit, "Sweet Seasons." In comparison, Taylor's "Mexico" almost sounded like a mellow Jimmy Buffett song.

The concert was performed in the round, with a large white stage in the center of the arena floor. The Mohegan arena's smaller size (about 10,000 seats compared to the 20,000 found in most larger venues), made for a much more intimate performance.

The two stars and their band ended the first set with Taylor's upbeat "Shower The People," while King belted out a stellar version of "(You Make Me Feel Like) A Natural Woman."

The second set featured even more well-known tunes. Taylor did "Your Smiling Face," "Sweet Baby James," which is the cowboy lullaby he wrote for his newborn nephew, and the touching, introspective "Fire and Rain," which got one of the biggest ovations of the night.

King matched him with plenty of hits of her own. "Jazzman" was sung at full throttle, while the wistful "It's Too Late" had the crowd singing along. The staccato pulse of "I Feel the Earth Move" provided even more proof that King is one of the most talented singer-songwriters of the rock era, and one hell of an entertainer.

Most in the audience would probably agree that King stole the show, but the mellower Taylor provided the evening with some great balance.

Aiding them in their mission was their band, consisting of long-time session musicians Danny Kortchmar on guitar, Leland Sklar on bass, and Russell Kunkel on drums, as well as Robbie Kondor on keyboards, Andrea Zonn on vocals and violin, and Arnold McCuller and Kate Markowitz on vocals. They were used all or in part for most of the show, and mixing it up improved the variety of the show a great deal.

While both stars were onstage throughout, Taylor and King performed only a few actual duets, including a stripped-down ballad version of "Will You Love Me Tomorrow," written by King and Gerry Goffin which became a hit for the Shirelles in1960. They also joined efforts on "You've Got a Friend," another song King wrote, but which Taylor made a # 1 hit.

The encore songs included King's "Up on the Roof," "How Sweet It Is," and "You Can Close Your Eyes."

While Elton John and Billy Joel have been touring together for many years, King and Taylor are doing this together for the first time in four decades, and the alchemy of the collaboration proved to be pure magic. Let's hope they keep this act on the road for a while. It's a winning combination that shouldn't be missed.