Angela Gheorghiu performs last month during the opening ceremony of the Vienna Opera Ball at the Vienna State Opera in Austria. (Martin Schalk/Getty Images)

Concerts of opera excerpts with orchestra are the three-ring circuses of the classical music world. Singers in an array of glittering gowns perform operatic highlights out of context, interspersed with orchestral overtures and interludes to get the crowd going, not unlike an electronic organ at the ballpark.

If you love opera and aren’t too hung up on good taste, such evenings can be delicious entertainment. And Angela Gheorghiu’s debut with the Washington National Opera on Saturday night, as part of the company’s new series of major singers in concert, was certainly entertaining — on some level. That’s not to say it was exactly good, but it was memorable.

Gheorghiu, 46, a beautiful woman with a beautiful voice, manages to sustain a reputation as both an international star and an under-appreciated artist, in part because her displays of what the opera world fondly calls “temperament” — in her case, pulling out of engagements if she doesn’t like a production, most recently from the Metropolitan Opera’s “Faust” — have made some companies reluctant to work with her. On Saturday, she played up the temperament, and even the eccentricity, by singing quite a bit of music she appeared not to know well.

It’s good to try new things. But the music’s unfamiliarity left Gheorghiu relying heavily on her music stand and Eugene Kohn, the conductor who led, or sometimes followed, the Washington National Opera Orchestra. Unfortunately, both artists had evident problems counting — Gheorghiu perhaps sharing the belief of diva stereotype that it is the conductor’s job to follow whatever she does. She kept coming in early or holding notes too long, leaving the orchestra skidding and sliding around her, even in what would appear to be the simplest of opening numbers, Handel’s “Ombra mai fu,” a tune so lovely and easy that irregularities are apparent even to classical music novices.

And the choice of repertory was odd. There were four arias on each half of the program, and four encores (although Gheorghiu wore only three gowns). The two opening arias — the second was “Deh vieni, non tardar” from Mozart’s “Nozze di Figaro” — were almost too simple to merit the term “warm-up,” and two others, “Vive amour” from Massenet’s “Cherubin” and “O nume tutelar” from Spontini’s “La vestale,” were fleetingly brief musical snippets.

This left four arias to stand in for the meat of the program, and even in these, Gheorghiu marshalled her resources. Dvorak’s “Song to the Moon” from “Rusalka” laid out her approach: She made lovely sounds that were often slightly underpowered, as if she weren’t quite singing with the full core of her voice, before hauling off at the end and delivering a full-throttle climax that created the illusion she had done something powerful and dramatic.

Her interpretation was at its most incongruous in “Pleurez, mes yeux” from Massenet’s “Le Cid,” which superficially may have seemed like the most dramatic moment of the evening — in part because Gheorghiu apparently forgot the words at one point and came in late with a string of fiery nonsense syllables. Her conclusion to this aria was equally passionate but had nothing to do with the notes Massenet composed, although it’s refreshing to hear an opera singer who’s able to improvise.

At least “Rusalka,” Massenet’s “Manon” and Catalani’s “La Wally” were all familiar territory — something the soprano signaled, in the final selection by turning her back on Kohn, leaving him scrambling to keep up. Still, it was her best and most authoritative singing of the evening.

This might have augured well for the encores, but instead Gheorghiu went fully over to the entertainment side and shimmied around the stage in her gold lamé dress with selections such as “I Could Have Danced All Night” and “Granada,” until one wondered whether she might start removing pieces of her outfit. “All the Things You Are” was sung into a microphone that was, fortunately, turned off, else it might have deafened the auditorium: a nice symbol of unrealized potential in an evening that never really seemed to find its center.

On March 17, the Washington National Opera will present Deborah Voigt in an evening of American classics called “DiVa Light.”