The Nationals recalled Hassell from Triple-A Rochester on Wednesday.
Hassell rebounded from a slow start at Rochester this season with a .339/.381/.559 batting line and four home runs so far in May. The 23-year-old's prospect shine has worn since he was included by the Padres as part of a trade package for Juan Soto, but the tools are still there and he could get an opportunity in the Washington outfield while Dylan Crews (oblique) is on the 10-day injured list and Jacob Young (shoulder) is banged up. Hassell is starting in center field and batting seventh Wednesday versus Atlanta in his major-league debut.