The purpose of this study was to analyze the effect of modification strategies based on the pedagogical principles of the Teaching Games for Understanding approach on tactical constraints of four 3v3 soccer small-sided games. The Game performance of 21 U-10 players was analyzed in a game similar to the adult game; one based on keeping-the-ball; another on penetrating-the-defense; and one on attacking-the-goal. Results showed that the modification of tactical problems had a significantly different effect on tactical-context adaptation (p < 0.005) and for developing passing, dribbling, shooting and getting free skills (p < 0.005). Small-sided games focused on keeping-the-ball and attacking-the-goal revealed a tactical complexity that was significantly different to the rest of the games (p < .005). With regard to the further investigation of the quality representative task design, these findings highlight the importance of knowing the effects that modification has on tactical constraints and the tactical complexity/technical difficulty involved in developing behaviors.