Tim McGraw and Faith Hill were an entertaining study in contrasts when their latest Soul2Soul tour played Mohegan Sun Arena on Friday, the first of two nights at the venue.

The duo — still the king and queen of the country music world 21 years after they wed — created honeyed harmonies when they sang together, but their voices, songs and onstage personas were distinctly their own.

Hill proved that her decade off from touring (during that time, she focused on raising the three daughters she and McGraw share) has done nothing to lessen her enthusiasm for performing or to weaken her voice. Hill was powerful and dynamic on everything, but most impressively on “Breathe.” “Breathe” was her crossover breakthrough in 1999, but, truly, Hill’s music always has leaned toward pop, as her Friday performance reminded us. Beyond her singing, Hill sometimes seemed physically taken away by the music, dancing with abandon.

McGraw, on the other hand, was all cool cowboy. His stage presence was potent but understated. His voice boasted all that McGraw-esque personality, with its slightly nasal twang, perfect for his determinedly country music tunes (think “Real Good Man” and “Something Like That”).

The duo started the night onstage together, running through a cover of Aretha Franklin and George Michael’s “I Knew You Were Waiting (For Me)” before diving into their own catalogs. They dueted on some songs and ceded the spotlight on others to their partner — sometimes merely stepping into the shadows, sometimes going offstage entirely — before coming together for the finale.

In a lot of ways, the concert was tightly planned, but there were a couple of memorable unscripted moments:

 • At the end of “Break First,” a new song from their upcoming (and first) duets album, McGraw and Hill were slowly walking toward each other in what was clearly a choreographed moment. Just as it looked as though they were going to lean in for a kiss, McGraw turned and walked away. That set off some bantering (or was it polite bickering?) between the two. She gave him a thumb’s down for the move, and they both tossed variations of the old “It’s your world, I’m just living in it” line at each other. He was chattering; Hill told McGraw he talked too much, and McGraw responded that he lives in a house with four women, so he gets a microphone, he’s going to say something. All I could think was: Oh, come on, you crazy kids! After a little more back-and-forth, they segued into another new song, the galloping “Telluride,” and continued with the show.

 • Toward the end of the night, as they sang “It’s Your Love,” the couple turned their backs to the arena to watch as family photos flashed on the video screen. Friday was the 20th birthday of their oldest daughter, Gracie, and Hill began crying as she watched pictures of their children and of their years together cycle by. “I hope this mascara is waterproof,” she said.

Speaking of birthdays, McGraw’s was this past Monday. He turned 50, and yes, he and Hill, who will turn 50 in September, look ridiculously good. McGraw’s handsome face peeked from under his signature black hat, and his clothes fit snugly, showing off just how much he must work out. Hill glowed with her cover-girl looks and flowing blonde locks.

While the concert had a whole lot going for it, it could have benefitted from a little more restraint in some aspects. The light show was intrusive, distracting from the performances instead of complementing them. The amplification of the band’s instruments should have been turned down to better showcase rather than compete with the stars’ voices.

And Hill’s set sometimes seemed as though things were perpetually dialed up to 10 (“Free” and “Piece of My Heart” in particular felt forced). Her voice is mighty, yes, but it would have been wonderful to also have heard her work her magic on, say, a solo ballad that would have given her a chance to showcase subtleties in her singing.

McGraw, meanwhile, scored his biggest crowd reactions with the one-two punch of “Humble and Kind” and “Live Like You Were Dying,” which showed that a good song in the hands of a good singer is all you need to move an audience. The fans sang along to the inspirational lyrics in one of those unified, feel-good concert moments.

The night ended with Hill and McGraw singing “I Need You” as they have often done: sitting on chairs facing each other, sharing one microphone, their hand resting on the other’s leg, staring with romantic intensity into each other’s eyes. When the number ended, Hill said to McGraw, if I heard correctly, “Come to Mama, Daddy.” They kissed, and she smiled, “That was so cheesy, but it was worth it.”

Opening the concert were The Shadowboxers. The musicians in this pop band from Nashville had an early-era-Maroon-5 onstage vibe about them. We might be hearing more from them: they noted that they’ll be soon heading into the studio to record their first “real” album ... with Justin Timberlake. Not bad, boys.