Competition is a powerful motivator in game-based learning but direct competition might bring negative influences on students when they lose the competition, such as damage to confidence. In this paper, we propose an approach to alleviate such negative influences - learning by pet-training competition, which provides an indirect competition environment to enhance students to learn through training their pets. That is, students learn Chinese idioms in a pet-training game scenario, and their mastery is related to the pets' strength to win the competition. In such environment, the competition result might be regarded as a matter whether students spend enough time in learning. This attribution might alleviate the negative influence that results from the direct competition.