CHICAGO — The friendly confines of Wrigley Field are a little too tight for the Big Ten.

The league announced Friday that Illinois and Northwestern had agreed to some drastic and unusual changes for Saturday’s game at the historic home of the Chicago Cubs — including running all plays toward the end zone that doesn’t happen to come within a foot or so of a padded brick wall.

That change, prompted by safety concerns, was approved along with a few others by the NCAA. And if the move sounds like a last-minute surprise, well, the Cubs thought so, too.

“The field dimension layout was delivered to the Big Ten approximately eight months ago and was approved by the conference,” Cubs President Crane Kenney said. “Last month, the field was built exactly to the dimensions previously approved by the Big Ten. Last week, a Big Ten official performed an on-site visit at Wrigley Field, participated in a field walk-thru and raised no issue with the field dimensions, painted lines and boundaries previously approved by the Big Ten.”

Big Ten commissioner Jim Delany released a statement that credited both schools with doing “significant” due diligence over the past 18 months. But he said the actual layout prompted the change to keep the players safe.

The problem is that the east end zone nearly abuts the right field wall, which has been heavily padded. The field is laid out east-west for the first football game at Wrigley since the Bears left for Soldier Field in 1970. The Bears games were played north-south, but there wasn’t much room then, either, and everyone decided the east-west layout was the way to go.