We introduce a new higher-order rewriting formalism, called Expression Reduction Systems with Patterns (ERSP), where abstraction is not only allowed on variables but also on nested patterns. These patterns are built by combining standard algebraic patterns with choice constructors used to denote different possible structures allowed for an abstracted argument. In other words, the non deterministic choice between different rewriting rules which is inherent to classical rewriting formalisms can be lifted here to the level of patterns. We show that confluence holds for a reasonable class of systems and terms.