A 47-year-old male ultramarathon runner presented with persistent discomfort in the anterior region of the left leg. The patient reported a snapping sensation in his left leg four weeks earlier while running an ultramarathon, followed by ecchymosis and functional impairment the next day. Physical examination revealed a palpable area of fibrosis in his anterior left leg. Ultrasound of the left leg identified a partially organized rupture of the distal third of the tibialis anterior muscle. The rupture had an extension of 36 x 10 x 27mm with associated muscle edema. The patient was treated non-surgically with a customized rehabilitation program and later returned to ultramarathon running. This case illustrates the importance of proper differential diagnosis and individualized rehabilitation programs to achieve optimum clinical and functional results.