Liga MX has been forced to postpone Thursday's season opener between Atletico San Luis and FC Juarez because of a spate of positive coronavirus tests.
The game is expected to be played on Monday, depending on further test results at FC Juarez, where there have been seven positive cases.
"We have seven positives out of 20 players from the group who were going to travel for the game. We'll see if any of those are ready for Monday to complete the team," Juarez president Guillermo Cantu told ESPN.
"The team is eager to play. We will use all the players we can. We hope that the second round of testing on players that had a positive won't get confirmed and come back negative."
A second Liga MX game, Mazatlan vs. Puebla, was postponed late on Wednesday pending COVID-19 results at Mazatlan. It was to be Mazatlan's Liga MX debut scheduled for Friday, but it is now set for Monday (11 pm ET).
Liga MX has endured a nervous few days leading up to the "2020 Guard1anes" season, over four months since the 2020 Clausura came to an end, with positive COVID-19 cases at a number of clubs.
The league released a 31-page document on its protocol to return amid the coronavirus pandemic, but squads have traveled during preseason and will be traveling around the country when the season begins.
Necaxa announced on Monday it had five positive cases in camp -- one player and four members of staff -- but Friday's game against Tigres is set to go ahead.
Chivas head coach Luis Fernando Tena won't be on the bench when Guadalajara takes on Leon on Saturday because he's in quarantine, having tested positive, and on Wednesday there were three more confirmed other positive cases at Chivas.
There have also been five confirmed positive cases in Atlas, three at Monterrey and one at Tigres over recent days.
Mazatlan, Cruz Azul, Toluca and Santos Laguna have previously reported positive cases, as well as seven match officials.
The Mexican government reported on Tuesday evening that there had been 6,859 confirmed cases and 915 deaths over the past 24 hours.