The holiday happens when Mariah Carey says it happens, which is why, on Thursday night at Madison Square Garden, the New Year's Eve countdown was maybe a minute after the fact. And more important, why Ms. Carey began the show suspended above the crowd in a red sled, drenched in red tulle, singing, "All I Want for Christmas Is You."
What, you're going to complain? Ms. Carey could have delivered that song in the middle of August and still pulled it off. Twenty years after her debut album, she remains a ferocious, inventive singer, right even when she's wrong. And surprisingly, she has become a versatile one, too, as famous for the epic-scale ballads she first made her name with as for her slick entrance into crossover hip-hop soul.
"Some people like my slow songs, and some people like my fast songs, and it gets so confusing," she said after "Touch My Body," early in her set. "What should I do?"
The answer was slow it down -- maybe a little too soon -- with the delicately strained "H.A.T.E.U.," from her new album, Memoirs Of An Imperfect Angel (Island). Throbbing and deliberate as a heartbeat, it was Ms. Carey at her isolated best, and a reminder that she's a complete anomaly in modern pop: an R&B singer who doesn't have to dance to prove her point. Apart from a few sashays during "Shake It Off," she barely broke form here, even when the tempos crept up to sweat level. (She made savvy use of her quicker older material, like "Make It Happen" and "Fantasy [remix]," which the band played during costume-change interludes until she rejoined them.)
So many of Ms. Carey's early hits were sturdy, bombastic and slow, and even though she has successfully sped up (and lightened up) in the last decade, it often feels as if she missed the sheer scale of her old material. Here, her band was on an elevated platform far behind her, and she was only sometimes surrounded by dancers. For large swaths of the night, she stood alone, and still.
Balladry is all but dead in popular music but Ms. Carey has learned how to game the system with songs that appear to have multiple tempos all at once, languorous vocals set against steady beats. In this grand setting it was clearer than ever that tracks like "We Belong Together" and "Angels Cry (remix)" are merely slow records masquerading as fast.
There wasn't quite enough time to explore such nuances, though: this was only half a concert, in spirit and in length. It was casual, with bursts of dancer disarray, and Ms. Carey talking to the crowd about the instructions she was receiving through her earpiece. After the countdown, dozens of friends and crew members came out onstage to dance even while Ms. Carey sang, making her into a disco diva delivering from the middle of the floor.
That lasted for a distractingly long spell, until Ms. Carey closed the night, a bit abruptly, with a sinus-clearing, room-shattering version of her 1993 hit "Hero," one of her most titanic ballads.
It hushed the crowd, but when Ms. Carey finished, she was back to giggles, picking up the banter with her husband, Nick Cannon, that she'd been having on and off since the countdown. They should be filmed, always, their blend of cute and beleaguered consistently entertaining.
A few minutes after midnight, when the crowd had been doused with confetti, she told Mr. Cannon that she wanted more. "Some more confetti?" he asked incredulously. "I'm going to see if I can work that out." She made a comment about her dress, to which Mr. Cannon replied: "You look hot in that. Madison Square Garden, tell her how sexy she looks!"
At the end of the night, Mr. Cannon tried to lead his wife offstage through a door at the back, but she resisted, saying she wanted to walk off the side, through the cluster of friends who had been standing there since the countdown. She play-pushed him aside and marched off. Mr. Cannon gave a knowing look to the crowd, pointed at his wife, grinned madly and ran after her.