Mendoza called the development "relatively good news," though he indicated Senga won't return for at least a month.

Senga, who has an MLB‑best 1.47 ERA, delivered 5.2 scoreless innings, allowing just one hit and five strikeouts, before collapsing after covering first base on a routine grounder.

Senga was seen to be making a play at first base after a ground ball hit by Nationals' shortstop CJ Abrams.