A case for a timepiece, of the wristwatch type, comprises a middle, a back and attachment members for attachment to a bracelet. The back is attached to the middle to pivot between open and closed positions, to use the timepiece as a table clock when it is in the open position. A first attachment member allows the attachment of a chain to use the timepiece as a pocket watch, and a second attachment member comprises at least one recess arranged so that one bracelet end can be inserted therein, in the open position of the back, and locked by the back when it is closed. The invention also relates to the corresponding timepiece and to an assembly comprising such a timepiece associated with adapted bracelet and chain. Advantageously, the transition from any configuration of the timepiece to another configuration can be carried out without using a tool.