A systematic literature review reveals that the role of AI as a sparring partner (SP) is often proposed but not systematically analyzed or defined. We propose the definition: An AI sparring partner (AI SP) interacts with users in a combination of a cooperative as well as a challenging, competitive mode, where AI is selected, customized or self-adapting to meet a level of skills that neither over- nor under-challenges the users. They can have the experience that they become better or are better than AI. AI as a SP can support creativity, extend viewpoints or foster learning and critical thinking either towards ideas and decisions or towards the AI itself. Sparring with AI can either be explicit, e.g. when AI simulates certain roles, or implicit, when AI is used to find out whether or how to perform better.