The one rule in pop music is, no rules. No formulas for success. No predictable patterns to be followed. What works for one performer does not always work for another, vice versa and, well, forget the whole thing . . .

Friday night at the Merriweather Post Pavilion, Melissa Manchester smashed her head against every pop style going and went nowhere. Saturday night, Anne Murray did the same and was simply smashing.

Murray, who started her career over a decade ago as a half-baked country crooner, has evolved into a full-fledged, well-rounded pop artist. Her performance featured a wide range of middle-of-the-road material and was not without its traditional and contemporary touches, yet Murray's distinctive vocal style and amiable, self-deprecating presence dominated the show.

From her hits such as "Snowbird" and "You Needed Me," to the Beatles' "You Won't See Me" and songs that were alternately gospel-tinged and bluesy, Murray maintained a sense of musical coherence that was both admirable and entertaining. Her strong, almost husky, voice negotiated ballads and fast-paced numbers with equal ease and she even transformed the Monkees' "Daydream Believer" into a first-rate song -- no small accomplishment.

There are many sides to Anne Murray -- all of them different and delightful.