Horrible news for the Nationals ... phenom outfielder Juan Soto has tested positive for COVID-19 -- and he's now out for the foreseeable future.
Of course, the Nats are opening the MLB season against the Yankees in just a few hours ... and Juan was expected to be the team's best hitter.
FYI, Soto is just 21 years old ... but he hit 34 home runs and logged 110 RBI last season, helping lead the team to its first-ever World Series title.
But, Juan came down with a positive diagnosis for coronavirus Thursday .