Present study aims to compare the physical and physiological demands of youth football players in official match and small-sided game. 17 players (16.0 ± 0.2 years of age) participated in the study. Seven small-sided games (GK33GK) and two official matches were monitored. In small-sided games, 71.9% of the time was spent above 90% of HRmax, against 44.4% in the official matches. The HRmax was higher (p <0.01) in the official match situation and the HRmean did not differ significantly (p ≥0.05). Sprints and total distance were higher in the small-sided games (p <0.01). During both situations, players present intense physical and physiological responses. However, the GK3x3GK elicits more efforts in high intensity and superior external demand per playing minute than official matches.