Miami Marlins first baseman Garrett Cooper, right-hander Jose Urena, outfielder Harold Ramirez, and catcher Jorge Alfaro have all tested positive for COVID-19, sources told Jon Heyman of MLB Network.
Urena was a late scratch prior to Sunday's game against the Philadelphia Phillies. Robert Dugger took his spot on the mound.
Both Cooper and Ramirez were in the starting lineup for games on Friday and Saturday.
Alfaro was placed on the IL with an undisclosed injury before Friday's season opener.
The players will likely quarantine at the team's hotel in Philadelphia for up to two weeks, according to Craig Mish of Sportsgrid. The rest of the roster is scheduled to fly back to Miami following Sunday's game.
Those who test positive need to produce two negative tests more than 24 hours apart before rejoining the team. As such, there's no timetable for their returns.
Marlins manager Don Mattingly said MLB should consider expanding the traveling taxi squad beyond three players to accommodate situations like this one, according to Joel Sherman of the New York Post.
While replacements haven't officially been named, Mish notes outfielders Monte Harrison, Travis Snider, and top prospect Jesus Sanchez are all possibilities.