MANSFIELD — If ever there were a Platonic ideal for an “American Idol,” inaugural winner Kelly Clarkson would surely be it. Whatever the show’s other triumphs — of which there were many — we can be grateful its spotlight found that voice. The competition might be staring down its final season, but Clarkson is still going strong.
Sunday night at the Xfinity Center before a near sell-out crowd, the Texas native was in peak form, delivering the hits with gusto, raising otherwise overlooked album cuts to memorable heights, and remaking the case for the restorative powers of pop music on a hot summer night.
In addition to that voice — by turns soulful, feather-light, powerful, and nearly operatic — Clarkson’s other best asset is the sheer, palpable joy she takes in performing with her eight-piece band, including three sizzling background singers.
Her phalanx of shiny anthems — “My Life Would Suck Without You,” “Mr. Know It All,” “Catch My Breath,” and giddy closer “Since U Been Gone” — were as sparkly as ever, and Clarkson added extra spice to each. Whether it was quick improvisational fillips or complete reworkings — as on red hot, precisely fitted mashup of her own sassy kiss off “Walk Away” with Mark Ronson and Bruno Mars’s “Uptown Funk” — the singer-songwriter had a treat up her sleeve.
The best ambassador for an album is a great live show, and Clarkson imbued lesser-known songs from “Piece by Piece” with a sense of a blood and grit that uniformly made them more compelling, particularly the ballad “Invincible,” on which she soared to her greatest vocal heights, and the title track, which movingly told her own tale of parental abandonment and subsequent healing.
Clarkson stripped things back mid-set for a three-song piano and voice medley of “Because of You,” “Breakaway,” and her duet with Jason Aldean “Don’t You Wanna Stay.”
Beaming throughout — even when she accidentally swallowed a bug — Clarkson also offered effusive praise for her openers, her band members, and other artists — that praise extended to a cover of Imagine Dragons’ “Radioactive” — and ceded the stage for an “Open Mic” performance by a young singer named Shannon from Millis who got a nice hand for her cover of Foo Fighters’ “Learn to Fly.”
Although Clarkson was joking when she remarked that she is improving with age like fine wine, she was also right on the money.
In addition to lending their voices to a spirited take of “Heartbeat Song” in Clarkson’s set, the powerhouse a cappella quintet Pentatonix — season three winners of “The Sing-Off” — opened with a dynamic set that showcased their remarkable technique.
They had their own fans in the house, as well, who reacted as enthusiastically to an astonishing medley of more than two dozen Michael Jackson songs as they did to the group’s originals, including “On My Way Home,” for which the crowd provided three-part harmony backing vocals.
At: Xfinity Center, Sunday nightSarah Rodman can be reached at firstname.lastname@example.org. Follow her on Twitter @GlobeRodman.