Purpose – This research seeks to examine the influence of sponsorship on spectators' consideration sets by investigating, in a naturalistic setting, whether sport sponsorship adds a prominent brand to spectators' consideration sets, with and without the explicit memory that the brand is a sponsor. Design/methodology/approach – A field study involved 1,084 visitors to a tennis tournament. For the control group (n=276), the interviews took place before the spectators entered the stadium; interviews with the exposed group (n=808) were conducted after they had attended at least one match. Three hypotheses related to consumer status and consideration set conditions were tested. Findings – Sponsorship can influence the likelihood that a prominent brand becomes part of the consideration set in a naturalistic setting, even without an explicit memory that the brand is a sponsor. This implicit sponsorship effect was limited to the memory-based consideration set of non-consumers of the brand. Originality/value – This study establishes an implicit sponsorship effect for prominent brands in naturalistic environments and contributes to a better understanding of moderating (boundary) conditions.