It's a rock-and-roll truism that the fewer vocals there are at a Santana concert the better, and Thursday night's show at the Merriweather Post Pavilion bore this out. Instrumentals dominated the show and even the vocal numbers featured long guitar intros, long guitar breaks and long guitar codas. True improvisation in rock-and-roll is rare, but guitarist Carlos Santana displayed both the technical mastery and the harmonic imagination to come up with fresh departures again and again.

In recent years, Carlos Santana has enjoyed a worthy foil in rock-funk keyboardist Chester Thompson, and last night the two took exciting, extended excursions -- both slow, unaccompanied duet reveries and high-speed chases over the band's rollicking Latin-rock rhythms. The show was hampered by mediocre British vocalist Alex Ligertwood and undisciplined bassist Benny Rietveld, but trap drummer Walfredo Reyes laid down an aggressive rock beat and conga drummer Armando Peraza overlaid it with Latin accents. Carlos Santana fit his skittering single-note runs and his vocal-style sustained phrases in and around the beat with unfaltering imagination.

London's Steele Pulse has long been the best non-Jamaican reggae band in the world, and in Thursday night's opening set, they tried to protect that reputation by updating the sound. They shifted their emphasis from guitars to keyboards, and they incorporated dub echo and toasting into their traditional reggae singing. The shift worked well because the band maintained its essential identity of David Hinds singing his biting social commentary over a solid roots-reggae rhythm and because toaster-keyboardist Selwyn Brown integrated the new elements so smoothly.