From the opening strains of their theme to "Flash Gordon," Queen promised to rock the audience at the Capital Centre on Sunday. And they kept the promise with a show that rarely flagged and often approached the group's concept of rock as a night at the electric opera.

The group that drew the largest single concert crowd in Argentine history--300,000 in Buenos Aires--made Washington another target in the quest for pop domination; their encores carried the message directly--"Another One Bites the Dust," "We Will Rock You" and "We Are the Champions." The last was positively anthem-like and one supposes that were Richard Wagner around today, his work might not be dissimilar.

Although some of Queen's newer songs have yet to attain the comfort of familiarity, there is a spectacular energy at the heart of its repertoire. Freddie Mercury, looking as if he'd been outfitted on the set of "A Clockwork Orange," is an appropriately mercurial front man, energetic and appealing and possessed of a convincing and clear rock tenor.

Brian May almost stole the show with his consistently fervent and inventive guitar work, particularly on "Get Down, Make Love," where he spent 10 minutes exploring excess without being overly wretched. May's dynamic digressions allowed the light system, heretofore merely spectacular, to almost outdo him with a combination of beautifully timed effects worthy of the "Poltergeist" or "Raiders of the Lost Ark" finales.

Other highlights included a surprisingly edgy "Crazy Little Thing Called Love," a pulsing "Under Pressure" (sans David Bowie but still compelling) and a gargantuan "Bohemian Rhapsody" that was not entirely classical but definitely a gas, and almost as good as the video. Queen's blatant disco hits--including "Bus," "Body Language" and "Hot Space," were overwhelming but not particularly convincing as funk, making Mercury come across as a plugged-in George Chakiris. Still, with remarkable sound and light systems to back them, Queen was a model of crunching efficiency and polished professionalism seldom matched in the rock arena.

Bill Squier, who opened the show, played a peculiar shell game. He tried to switch his songs around faster than the ear could follow, but they ultimately revealed themselves to be pretty much the same under the bare frames: In fact, they sounded like hard-core REO Speedwagon. Squier's voice conjured up REO's Kevin Cronan . . . and Roger Daltrey . . . and Rod Stewart . . . and Freddie Mercury (particularly on "The Stroke," his own rehashed Queen funk), but it surrendered too often to the slight challenges of his melodies. Squier has an instinct for commercial hooks, but right now he doesn't have enough to hang on them.