A day after the Big Ten announced it would play a conference-only schedule in all sports this fall, the Pac-12 voted to do the same Friday during a virtual meeting of athletics directors, university presidents and conference officials.

The Pac-12 CEO group's decision will delay the start of fall seasons, including football.

One of the reasons the Pac-12 decided to push back the start of the football season was a concern that UCLA and USC would not be ready to play in early September because of coronavirus cases in the Los Angeles area, sources told ESPN.

The Bruins were slated to open the season against New Mexico State at home on Aug. 29; the Trojans were scheduled to open against Alabama at AT&T Stadium in Arlington, Texas, on Sept. 5.

"USC AD Mike Bohn and I had multiple conversations over the last several months, and we were both planning on playing the football game on September 5 in Arlington," Alabama athletic director Greg Byrne said in a statement. "With the Pac-12's decision to move to a conference-only schedule, we will do our best to adjust. What that looks like is to be determined."

The Pac-12's decision to play only conference games means Notre Dame will not face USC for the first time since World War II. The Irish and Trojans have played each other every season since 1926 except for 1943-45 because of the war. Notre Dame will also lose its rivalry game against Stanford, which has been played every year since 1988, except for 1995 and 1996. Because of the Big Ten's decision, Notre Dame's contest against Wisconsin at Lambeau Field in Green Bay also won't be played.

The move also creates scheduling dilemmas for BYU and Hawai'i, which will both have to find new opponents for each of their first four games. As it stands now, neither school has a game scheduled until the first weekend in October. BYU was scheduled to play Utah, Michigan State, Arizona State and Minnesota the first four weeks and Stanford in the regular-season finale, and Hawai'i was slated to play Arizona, UCLA, Fordham (the Patriot League banned flying for the upcoming season) and Oregon.

"Obviously with three Pac-12 teams on our football schedule, today's decision affects us more than others," Hawai'i AD David Matlin said in a statement. "We are disappointed because not only were we looking forward to opening the season at Arizona, we were excited to host UCLA for the first time in over 80 years and renew a series with Oregon. However the decision was made in the best interest of student-athlete health and wellness and we support that and will move on accordingly with the rest of our schedule."

Colorado State, UNLV, Utah State and FCS program Portland State were all scheduled to play two games each against Pac-12 foes.

The decision also included men's and women's soccer, and women's volleyball, and the league said it was delaying the start of mandatory athletic activities "until a series of health and safety indicators, which have recently trended in a negative direction, provided sufficient positive data to enable a move to a second phase of return-to-play activities."

"The health and safety of our student-athletes and all those connected to Pac-12 sports continues to be our number one priority," Pac-12 commissioner Larry Scott said in a statement. "Our decisions have and will be guided by science and data, and based upon the trends and indicators over the past days, it has become clear that we need to provide ourselves with maximum flexibility to schedule, and to delay any movement to the next phase of return-to-play activities."

The Pac-12 announced later Friday that Scott had tested positive for the coronavirus.

The league said student-athletes who choose not to participate in intercollegiate athletics during the coming academic year because of safety concerns about COVID-19 will continue to have their scholarships honored by their university and will remain in good standing with their team.

"Competitive sports are an integral part of the educational experience for our student-athletes, and we will do everything that we can to support them in achieving their dreams while at the same time ensuring that their health and safety is at the forefront," said Michael Schill, the Pac-12 CEO group chair and president of the University of Oregon.

Officials from the ACC, Big 12 and SEC told ESPN on Friday that they probably will wait until the end of July to make a decision on scheduling for football this fall amid the coronavirus pandemic, if the season can be played. SEC athletic directors are scheduled to meet at the league's office in Birmingham, Alabama, on Monday. ACC officials also are scheduled to meet next week.

Adam Rittenberg contributed to this report.