All those jazz purists who have been sneering at Pat Metheny for years are about to discover just how wrong they've been. Metheny has undertaken the daunting challenge of coleading Ornette Coleman's first studio sessions since 1979. And if Metheny hasn't quite matched the wily old jazz master, he has more than held his own and has stimulated Coleman into one of the great jazz albums of the '80s: "Song X" (Geffen, GHS 24096).

The album pulls together the different segments of Coleman's varied career into a new musical synthesis. Metheny plays a respectful, supportive role as producer and second soloist, but the young guitarist has created the perfect environment and foil for the older saxophonist. The dynamics are far more varied than on Coleman's frenetic recent records, and his melodic and harmonic gifts are clearer than they've been in years.

Suddenly, Coleman's roots (Texas R&B and post-bop jazz) and his two separate jazz revolutions (1958's free-jazz and 1977's harmolodic-jazz) all seem part of the same continuity. Metheny and a brilliantly assembled band respond to every facet of Coleman's music and seem to assure that this continuity will survive into the future.

On bass is Charlie Haden, the probing, prodding player who anchored Coleman's first famous quartet. On drums are two very different players: Jack DeJohnette, whose light, melodic touch reflects his composing and piano skills, and Coleman's son Denardo, who developed a hard-driving, explosive style in his father's harmolodic Prime Time Band. This same quintet plays at the Warner Theatre May 5.

Ornette Coleman has long been one of Metheny's biggest heroes, and the young guitarist has regularly taken time from his lucrative Pat Metheny Group to explore Coleman's free-jazz heritage. In 1981, Metheny put together a quintet that included Coleman alumni Haden and Dewey Redman for the Coleman-influenced "80/81" album. In 1984, Metheny joined Haden and former Coleman drummer Billy Higgins in a trio that recorded three Coleman tunes on "Rejoicing."

Because Metheny is such a melodic soloist and such a focused arranger, he has stimulated Coleman to showcase the latter's remarkable gifts for melody and harmony. Unlike the electric guitarists in the Prime Time Band, who played their own simultaneous solos with Coleman's alto sax, Metheny tries to shadow Coleman harmonically and creates a musical dialogue.

You can hear this on the album's one unaccompanied duet, "Song X Duo." Coleman plays one of his characteristic solos: a series of lilting alto sax phrases that tumble forward without pause or repetition in an exhilarating stream of consciousness. Metheny keeps up with him for a while with a tumbling series of counterpointed single-note phrases before turning to chordal harmonies.

If Coleman is more melodic than he has been in years, this record forces Metheny into the most complex, jagged music he's ever played. Three tunes are done in the freewheeling harmolodic style of Coleman's recent bands. "Song X" is a fast, agitated piece that has phrases of different lengths shooting off in different directions, with all five musicians soloing at once. Coleman's strong sax line provides the center of gravity, though, and everyone else takes their rhythmic and harmonic cues from him.

"Endangered Species" is an even wilder exercise: 13 minutes of high, shuddering sax and drum phrases, repeated over and over at supersonic tempos until they become almost trance-like. On "Video Games," Metheny uses his guitar synthesizer to good effect: He sprays electronic tone colors to create a musical field for Coleman to romp in.

The rest of the album features an old-fashioned swing and restrained subtlety. "Mob Job" recasts the Prime Time Band's "Job Mob" as a relaxed, bluesy tune with a fiddle solo by Coleman and some country jazz comping by Metheny. Coleman and Metheny cowrote "Kathelin Gray," which boasts a lovely melody that they caress with help from Haden's stately bass melody and DeJohnette's restrained cymbal work. The two coleaders also cowrote "Trigonometry," a patient, pause-filled melody set against Haden's sprinting bass.

Coleman has been a reclusive figure in recent years. He has rarely performed in public, and his last two albums, released in 1982, contain recordings from 1979 and earlier. If he had done nothing else, Metheny would have performed an invaluable service by creating the right setting to make Coleman want to record again. He has done much more, though: He has turned an all-star band into a cohesive group and an experimental collaboration into a triumphant album.

While Metheny records and tours with Coleman, Metheny's long-time keyboardist, Lyle Mays, is pursuing his own solo project. His first solo album, "Lyle Mays" (Geffen, GHS 24097), is much closer to the sound of the Pat Metheny Group than "Song X" is. Mays even successfully imitates Metheny's guitar synthesizer leads with his own keyboard synthesizers. If Mays' album lacks the cracking tension and bold risks of the Metheny/Coleman project, it's nonetheless full of strong melodies, graceful piano work and atmospheric harmonies.

Mays has assembled a superb band, including bassist Marc Johnson and drummer Alex Acuna, who join him in a trio performance at Lisner Auditorium tonight. Soprano saxophonist Billy Drewes plays Wayne Shorter-like solos against Mays' Joe Zawinul-like synthesizer music scapes on "Teiko" and "Ascent." Mays has written striking melodies for "Highland Aire" and "Slink," which enjoy the buoyant momentum of the Metheny Group's most popular numbers. Occasionally, though, Mays does lapse into the folksy sentimentality of George Winston's playing.

Mays' new bassist, Johnson, has also released his first album, "Bass Desires" (ECM, 25040-1). Johnson's arrangements bring a refreshing lyricism and restraint to the jazz-rock field. Johnson and ex-Weather Report drummer Peter Erskine provide a flexible, restless through-line to each tune. The two guitarists, John Scofield (Charles Mingus and Miles Davis) and Bill Frissell (also on Mays' album) play short, well-defined phrases that make their statements and get out. This leaves the record free of clutter and makes the precise inventive variations that much more effective.