Gray was activated to the Nationals' 26-man roster Sunday and will start Monday against the Phillies, Mark Zuckerman of MASNSports.com reports.
Gray made his first MLB start July 25 for the Dodgers before being traded to the Nationals on Friday, and he'll debut for his new team Monday. The 23-year-old was one of Los Angeles' top prospects and allowed six runs on seven hits with a 13:5 K:BB in eight innings across his first two appearances in the majors.