This study aimed to evaluate the changes in leg-power generation that accompany competitive badminton, as simulated in a badminton field test (FT). [Participants and Methods] Fifteen male badminton players with 1-2 years of experience performed five repetitions of an FT involving rapid and randomly assigned shuttle-run movements between markers distributed around a badminton court. Repetitions were separated by a 1-minute rest period. Peak mechanical power, obtained from the serial vertical jump tests, was used to estimate fatigue and performance reduction. [Results] Decreases in distance and time were significantly different in each of the five FT repetitions while maintaining the same speed for the condition. The peak mechanical power and fatigue index significantly declined. The reduction in the peak mechanical power percentage (11.78-35.49%) was in the acceptable peak mechanical power range for each FT set. These results were confirmed by the significant increase in the participants' blood lactate concentration levels, the rating of perceived exertion, and heart rate. [Conclusion] Leg-power generation could gradually be decreased in badminton competition as indicated by a badminton field test.