Major League Soccer announced two match postponements on Saturday after two positive Covid-19 tests each for Minnesota United players and Columbus Crew staffers.
The league postponed Sunday's Columbus at Orlando City match and Minnesota's match at FC Dallas over health and safety concerns.
No immediate reschedule date was announced.
The positives are the latest involving MLS clubs. The Colorado Rapids have had their past four matches postponed due to a coronavirus outbreak on the team, the latest being a scheduled Saturday affair against the Los Angeles Galaxy.
Columbus, 9-3 with four drawn, ranks third in the Eastern Conference with 31 points, trailing Philadelphia on goal difference with Orlando one point adrift.
Minnesota, 6-5-5, ranks fourth in the Western Conference on 23 points, two ahead of sixth-place Dallas.
MLS regular-season matches are set to run through November 8 with a knockout playoff format leading to the championship match on December 12.