Purpose: To examine the internal and external load imposed by long sprint ability–oriented small-sided games (SSG) using different ratios of players to pitch area (densities) in soccer players. Methods: A total of 19 professional soccer players from the same soccer club (age = 17.1 [0.3] y, height = 1.76 [0.69] m, and body mass = 69.7 [9.4] kg) participated in this study. Players performed 4 × 30-s (150 s recovery) all-out 1-vs-1 SSG considering 300, 200, and 100 m² per player (48 h apart). Players’ external loads were tracked with global positioning technology (20 Hz). Heart rate, blood lactate concentration (BLc), and rating of perceived exertion characterized players’ internal load. Peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT). Results: SSG₃₀₀ produced higher BLc than SSG₂₀₀ (moderate) and SSG₁₀₀ (large). The SSG₃₀₀, SSG₂₀₀, and SSG₁₀₀ BLc were 97.8% (34.8%), trivial; 74.7% (24.9%), moderate; and 43.4% (15.7%), large, of the NMT30s peak BLc, respectively. Players covered more distance at high intensity during the SSG₃₀₀ than in other SSG conditions (huge to very large differences). High-intensity deceleration distance was largely lower in SSG₂₀₀ than in SSG₃₀₀. SSG₁₀₀ elicited very large to huge and large to very large lower external load values than SSG₃₀₀ and SSG_200, respectively. Conclusions: The main finding of this study showed an inverse association between ball-drill density and internal/external loads in long sprint ability–oriented SSG. The SSG₃₀₀ provided BLc closer to individual maximal, thus satisfying the all-out construct assumed for the development of long sprint ability. Further studies using the SSG₃₀₀ as a training intervention and/or investigating other different SSG formats using the same density are warranted.