Purpose: To test whether ultrasound-triggered pre-landing quadriceps focal vibration acutely improves knee mechanics and coordination during single-leg drop landings under fresh vs combined cognitivephysical fatigue. Methods: Twenty-four healthy males (25.4 +- 2.1 years; 175.0 +- 3.1 cm; 73.2 +- 4.9 kg) performed randomized-crossover single-leg forward drop landings. Quadriceps vibration was off or ultrasonically triggered. Landings were tested pre- and post-combined fatigue (15 min dual-task cognitive +90 s burpees). Results: In the pre-fatigued state, vibration increased peak knee flexion angle by 2.67% (P - 0.001) and knee flexion range of motion by 1.36% (P - 0.008), reduced knee flexion work by 1.69% (P - 0.024), peak vertical ground reaction forces loading rate by 6.67% (P < 0.001), peak patellar tendon force by 5.92% (P < 0.05), time to stabilization by 3.88% (P - 0.003), and maximal diagonal line length by 2.32% (P - 0.008). Post-fatigue, vibration increased determinism (P - 0.023), Shannon entropy (P - 0.041), and dynamic time warping distance (P - 0.045) without significant kinematic or energetic changes. Conclusions: Pre-landing quadriceps vibration acutely enhances sagittal-plane landing biomechanics, increasing knee flexion, reducing eccentric work and impact loading, and improving adaptive coordination in fresh conditions, with no significant effects under combined fatigue.  Kulcsszavak: focal muscle vibration, single-leg drop landing, patellar tendon loading, fatigue, injury prevention