So how does Debbie Gibson, pop's other reigning teen queen, fare against Tiffany?
Where Tiffany, 16, demonstrated only marginal vocal ability and stage presence here last month, Gibson, 17, exhibited a vitality and charm Monday night at the Greek Theatre that recalled the most triumphant moments of Olivia Newton-John's 1982 "Physical" tour.
Comparing Gibson to Newton-John may strike some as damning with faint praise, but Newton-John--widely dismissed as a pretty non-talent early in her career--had matured by the time of the "Physical" shows into a winning performer and frequently accomplished vocalist.
However, the first influence that came to mind as Gibson, a New Yorker who writes most of her own material, came racing on stage Monday was Madonna.
Not only did Gibson (like Madonna) have two stylishly dressed male dancers at her side as she moved about with enough energy to qualify as an aerobics instructor, but the multilevel stage had a high-tech look that underscored the contemporary dance-pop flavor of Gibson's upbeat numbers.
Yet there was little hint of Madonna's aggressive sensuality in Gibson's manner or songs. As she skipped about on stage, Gibson seemed as wholesome as a high school cheerleader, and her songs (including "Staying Together" and "Play the Field") deal with teen relationships in a way that would rarely earn anything other than a G rating.
As the evening progressed, however, it became clear that Newton-John (who exhibited a similar aerobic energy, sparkling smile and even blonde bangs) was a closer parallel.
Both singers draw upon a rather straightforward pop tradition rather than the more soulful elements of country and blues (in their vocals and arrangements), or the more substantial themes of rock and folk (in their lyrics).
While that pop emphasis may ultimately limit Gibson's significance, she has already demonstrated the ability to come up with some remarkably appealing hits, including "Out of the Blue" and "Only in My Dreams."
Not everything Gibson has written is as noteworthy ("Shake Your Love" is anonymous dance-club fodder and "Fallen Angel" is mushy and cliched), but there were moments Monday that suggested Gibson is capable of both greater consistency and growth.
The first sign was when Gibson, who had traded in her opening costume (a carnival mini-dress) for a sequined letterman's jacket and jeans, stepped away from her old material for some nostalgia.
Where Tiffany lumped a string of '50s and '60s songs into a careless oldies medley during her show, Gibson sang the Five Satins' classic 1956 ballad "In the Still of the Night" with a surprisingly rich edge.
Equally impressively, Gibson followed "Night" with a new song that will apparently be in her next album. Titled "Lost in Your Eyes," it is an especially soulful and dramatic expression of romantic innocence and desire.
Perhaps the best moment, however, was near the end when she went into "Only in My Dreams." The song is about romantic fantasies, but Gibson paused at the start of the number.
As she stood in the glare of the stage lights and stared out at the enthusiastic, cheering crowd, she seemed overwhelmed by the fact that she, just a month out of high school, has been able to make her own pop music fantasies a reality.
Whether it was a genuine moment of emotion or a bit of theatrics programmed into the show, it was touching in a way that made the song itself seem all the more disarming.
As she and her six-piece band and three female backup singers left the stage, the capacity crowd--sprinkled with lots of young TV sitcom stars who kept the teen autograph hunters in the audience busy during intermission--stood and cheered, "Debbie, Debbie, Debbie" with an eagerness that seemed more urgent and heartfelt than the usual teen exuberance.
Gibson's next album will tell us a lot about how just how good this youngster is, but she's certainly off to a fast and promising start.
Opening for Gibson was Times Two, a duo dressed in sporty tuxes who salute such influences as Elvis and the Beatles in the liner notes on their Reprise album, but whose music itself suggests more hours spent in New York discos listening to Hall & Oates and, perhaps, Michael Jackson.
You hear the former duo's influence in the tight song construction and (alas) in the synthetic arrangements and hollow sentiments, with signs of Jackson's breathless, whispering punctuation in some of lead singer Shanti Jones' vocals. The San Francisco-based duo also must have spent a lot of time studying Jackson's moves, which they try to mirror--with frequently embarrassing results.