Only one end zone will be used for offense Saturday at Wrigley Field for the Illinois-Northwestern game because of safety concerns, the Big Ten announced Friday, and the Chicago Cubs said the decision caught them by surprise.

Whichever team is on offense Saturday will head toward the west [left] end zone. AP Photo/Charles Rex Arbogast

NCAA rules state the field dimensions must have adequate space surrounding the playing surface: "Limit lines shall be marked ... 12 feet outside the sidelines and the end lines, except in stadiums where total field surface does not permit. In these stadiums, the limit lines shall not be less than 6 feet from the sidelines and end lines."

Wrigley's east end zone is a few feet away from the right-field wall, and although there is padding, there were concerns players could be injured there.

Northwestern coach Pat Fitzgerald had said this week he would have different game plans for each end zone to avoid the possibility of injury.

When a team is on offense Saturday, it will be positioned to head to the west end zone.

"Though it's not ideal, it's the right thing," Northwestern athletic director Jim Phillips said on "The Waddle & Silvy Show" on ESPN 1000. "We've been planning for this for a while, there were no surprises. The field came out the way we thought, it ended up maybe being a little closer with some of the padding.

"As we looked at it -- the visual aspect of it -- this week, we just felt there was a low probability that something would happen. ... And the more we thought about it, the more we talked about it, we looked at it, we just felt like this was something we needed to do. And it was complete uniformity between the Big Ten conference, and Northwestern and Illinois. At the heart of it was to make sure we had done everything we could to make it safe."