The Big Ten on Friday received a letter from the NCAA Rules Committee confirming that the football configuration at Wrigley Field for the Northwestern-Illinois game didn't meet standards for compliance.

In the letter, Rogers Redding, the secretary-rules editor for the committee, writes that the field configuration didn't meet the minimum specifications outlined in the NCAA Football Rules Book. Redding on Wednesday notified the Big Ten of a compliance issue with the proposed field at Wrigley, setting off discussions that led to the significant rule changes.

Redding writes: "The field as it currently appears to be configured does not meet the requirements of NCAA Football Rule 1-2-3.a, which deals with the amount of space required outside the sidelines and end lines [a minimum of six feet]. This rule is in place to allow student-athletes room when they leave field of play to do so safely. At one end zone, there appears to be six inches of space between the end line and a wall."

Redding adds that he would be willing to assist the Big Ten with alternative plans to "bring the field into compliance" or adjust rules to protect player safety. "That said, please note that the NCAA will not assume any liability for this contest if it is played with the current field layout, or any other layout not in compliance with NCAA rules," Redding writes.

The letter was addressed to Big Ten commissioner Jim Delany but also had copies sent to athletic directors Jim Phillips of Northwestern and Ron Guenther of Illinois.