A diamond relay channel in the presence of interference which is non-causally available only at one relay is considered. The interference signal may have structure, for example it could come from another source communicating with its own destination. However, the external interferer is not willing to adjust its communication strategy to minimize the interference and is considered to be fixed. Two approaches are possible to mitigate the interference: exploiting the structure or treating it as unstructured. Using these approaches, bounds for the Gaussian half-duplex diamond relay channel based on two transmission time patterns are established. The importance of exploiting the interference structure and transmission time patterns are discussed.