Purpose: To examine the relationship between variable lower-limb coordination and shoulder joint kinetics and kinematics in the high-performance flat first serve in tennis.Methods: Three-dimensional data describing three flat serve (FS) techniques, each executed with varying lower-limb involvement: foot-up (FU), foot-back (FB), and minimal leg drive (ARM), as performed by 12 high-performance male players were recorded using a 12-camera Vicon MX motion analysis system operating at 250 Hz. A discriminant analysis determined the lower-limb kinematics that distinguished serve technique, and by extension, leg drive. A total of 18 one-way ANOVA ascertained statistically significant differences in the kinematic and kinetic variables considered to relate to or represent shoulder joint loading in FU, FB, and ARM serves.Results: The lower-limb kinematics shown to best discriminate between service techniques were range of rear and front knee joint extension, and peak angular velocity of rear knee joint extension. The forward swings of the FU (43.6 ± 3.0 m·s-1, P <0.05) and FB (42.6 ± 3.1 m·s-1, P <0.05) techniques were characterized by higher peak racket speeds than those generated in the ARM (39.4 ± 3.4 m·s-1) serve. Regardless of stance and leg drive, similar pre- and postimpact shoulder joint kinetics were developed.Conclusion: Knowledge of a server's range of front and rear knee joint extension as well as his/her peak angular velocity of rear knee joint extension is sufficient to ascertain the stance and quality of leg drive used. When facilitated by a leg drive, high-performance players generate similar resultant preimpact racket velocities independent of stance. With no leg drive, players develop lower resultant racket velocities. Comparable shoulder joint kinetics, however, evolved from the differential lower-limb mechanics that characterized the FU, FB, and ARM techniques.