It used to be that you never knew what to expect from Mark Morris.

With a confidence and musicality that stunned the dance world, the mop-topped iconoclast turned out audaciously frisky, barefoot romps to Handel odes and Brahms waltzes. His musical tastes were as broad as his funny bone: At a Morris concert you were as likely to hear something disarmingly contemporary -- say, the country swing of Bob Wills and the Texas Playboys -- as you were Vivaldi or Bach. And he might dance an oddly tender duet with a miniature windup truck, or scrunch up his pianist in front of a toy piano, onstage, to plinkety-plink some high-art classical score.

Increasingly, though, Morris is growing predictable.

The Mark Morris Dance Group, now in its 27th year, tours with the MMDG Music Ensemble, and chamber music is almost always on the menu. The program over the weekend at George Mason University followed what has become a fairly routine format: four short works, serious classical music, abstract dancing that mirrors the music in all its prismatic complexity. And while Friday's performance featured fine musicianship and potent dancing, the evening as a whole felt dry and juiceless.

Is Morris turning away from his youthful playfulness, and pushing importance? The newest work on the program, "Candleflowerdance," is dedicated to deep thinker Susan Sontag. We braced for an intellectual experience, and Morris delivered: the music, performed by Steven Beck (an endurance pianist), was Stravinsky's Serenade in A for solo piano. It is a calculated, chilly work, bouncing sharply but without joy.

The dancers were casually dressed in slacks and T-shirts, with a few bright colors in the mix, but they were as detached as the music. They looked lost in their thoughts, and we weren't welcome there.

The candles and slim vases of flowers on the stage did little to warm the atmosphere. This work felt like an awkward party that one was eager to leave.

Despite its title, "Sang-Froid" (meaning "coldblooded," in the sense of being cool and composed), performed here in 2000, was the most inviting work, set to familiar Chopin etudes reinterpreted by what might be office mates on a trust-building retreat. It's a lesson in group dynamics, set to sublime piano tunes, but there's nothing precious or delicate about the sport taking place onstage.

The work has a folk-dance feel, with linked arms and heavy stamping, and there are a few casually tossed-off ballet steps, and also a big, panting game of red rover. It's all robust and extroverted, and it gives the familiar music new vigor.

Two other familiar works filled out the program: "The Argument," in which three couples show us three nuanced versions of discord, accompanied by Robert Schumann's "Funf Stucke im Volkston," and "Grand Duo," a large, full-company work in dark, mysterious, epic-heroic mode, whose chief momentum comes from the hot-blooded, jazz-splashed Lou Harrison score, "Grand Duo for Violin and Piano."