The term "after-pieces" refers to the closing acts of a theatrical performance. It has no exact opposite or antonym, but one could use words like "opening acts," "pre-show entertainment," or "preliminary performances" to describe the first acts of a theatrical presentation. Another opposite term could be "prelude," which is a musical or introductory performance that precedes the main event. While there isn't a direct antonym for after-pieces, it is possible to describe the opposite direction of a performance, from start to finish. In the end, the antonym of after-pieces ultimately depends on the context in which it is used.