After being on the road for more than a year, Rod Stewart might be excused the apparent weariness that muffled early portions of Wednesday night's concert at the Merriweather Post Pavilion. For a while, the 54-year-old Stewart seemed emotionally disconnected from his performance, singing with his eyes closed, as if daydreaming about a much-deserved vacation. It was rock he rote, with Stewart prancing, preening and hitting all the notes, but not always convincingly. Happily, he eventually reconnected to the gritty passion that's always marked his best work, inspired by both classic material and the audience's fervent response.

Stewart's generous showcase--26 songs and no opening act--kicked off with "Tonight I'm Yours," a rollicking "Get Back" and the giddy observation that "Some Guys Have All the Luck." The trim and peripatetic Scotsman then delivered the first of several rousing anthems, the celebratory "Forever Young," which provoked the first of the evening's many audience-led choruses. But "I'm Losing You" was marred by a totally uninspired solo from drummer David Palmer, while the singer's cover of Cat Stevens's "The First Cut Is the Deepest" seemed raggedly lazy.

Stewart, whose raspy vocals seem to have lost none of their power or charm, regained his momentum with a lovely reading of his first major hit, the Tim Hardin ballad "Reason to Believe," followed by the genial shuffle of "You're in My Heart" and the romantic pleadings of "Stay With Me" and a somewhat overblown "Lost in You."

The show finally took off when Stewart steeped himself in the soul music that originally inspired him, notably an impassioned reading of the Impressions' stately "People Get Ready" (with an incendiary guitar solo from Paul Warren). After that, the highlights came more frequently: a sweetly graceful reading of Van Morrison's "Have I Told You Lately That I Love You," the soaring Scottish-flavored "Sailing," the insistently seductive "Tonight's the Night," a still-invigorating "Maggie May" as encore.

There were also hard thumpers, from "Infatuation" to such giddy, over-the-top dance floor machinations as "Hot Legs" and "Do Ya Think I'm Sexy" (the audience clearly did). The problem was that on these hard-charging, up-tempo numbers, Stewart tended to be overwhelmed by a seven-piece band that offered little in the way of dynamic subtlety, often resorting to arena rock cliches in both sound and gesture. The singer's not above that himself, but on the lithe, limber Stewart, it looks good.

Stewart's three backing singers--Lamont Van Hook, Fred White and Dee Harvey--did enrich the sound on his Sam Cooke tributes, a genially reggaefied version of "Cupid" and flat-out exuberant readings of "Twistin' the Night Away" and "Having a Party." Which is what Stewart had in mind all along, working at it hard enough to require six shirt changes in two hours.