Leaderboards are a popular way to implement competition, trigger social comparison, increase participation, and provide goals and performance-based feedback to the players. Even though game-based learning has become more common in education, relatively little is known about the motivational power of leaderboards in team-based educational settings. This paper aims to contribute to this gap by exploring to what extent leaderboards motivate players in collaborative and competitive game-based learning context. The meaning of leaderboards was studied in a team-based math game competition relying on intra-classroom collaboration and inter-classroom competition. The findings suggest that the team rank, team commitment, and enjoyment of the game predicted leaderboard motivation. The results revealed that even though leaderboards were motivating in general, players whose team did not succeed well in the competition were less motivated. It seems that leaderboards may facilitated collaboration but the collaborative element of the competition did not totally reduce the negative effects of the used infinite leaderboard. These findings disclose some drawbacks of an infinite leaderboard design. To overcome this problem, we suggest some ways to redesign leaderboards for educational use. Finally, we discuss implications of the research for using leaderboards in game-based learning settings, factors affecting leaderboard motivation, and leaderboard design in general.