Reilly wins Boston Marathon's women's wheelchair
Reilly finished in 1 hour, 37 minutes and 36 seconds on Monday, one second ahead of defending champion Tsuchida.
Last year, Tsuchida beat Reilly by nearly seven minutes.
Reilly and Tsuchida battled throughout, with Tsuchida briefly breaking away around the 18-mile mark before Reilly closed the gap.
Diane Roy of Canada finished third, five minutes behind Tsuchida.
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