As part of the NFL’s 100th anniversary celebrations, the Cincinnati Bengals practiced Sunday at Welcome Stadium in Dayton, Ohio, the city where the first NFL game took place in 1920 between the Dayton Triangles and the Columbus Panhandles. Things took a sour turn, however, about an hour into the session when star wide receiver A.J. Green landed awkwardly on his left foot after he and cornerback Dre Kirkpatrick went up to battle for a ball thrown by Andy Dalton.

Green left the stadium later Sunday on crutches, and ESPN’s Adam Schefter reports that an MRI exam revealed torn ligaments in his left ankle. Green, a Pro Bowler in each of his first seven NFL seasons, will be out six to eight weeks and most likely will not be ready for Cincinnati’s season opener against the Seahawks on Sept. 8.

Fellow Bengals wide receiver Tyler Boyd stopped short of saying that Green’s injury was directly caused by the turf but didn’t mince his words when describing it.

“The turf was terrible,” Boyd said, per ESPN. “I couldn’t run any routes out there. I’m falling all over the ground. It was bad. It was rocks, pebbles out there. Man, it was somewhere we shouldn’t have been. I’m not trying to say any excuses, but it is what it is.”

The Bengals cleared the field for use before the practice, Schefter reports, and Coach Zac Taylor disagreed that Green’s injury was caused by the field, saying “I don’t think the turf had anything to do with it."

Sports Illustrated’s Albert Breer reports that the NFL originally wanted the Bengals to practice at Dayton’s Triangle Park, where the 1920 game was played and planned to spend $440,000 to build a practice field there, but a Native American group raised concerns that the park was located atop an ancient burial ground and the plan fell through. So the league had the practice at Welcome Stadium, where the University of Dayton plays its home football games.

Breer added that several Bengals staffers were “frustrated that Green’s injury happened on a field that they saw as subpar.”

It was another tough break for Green after he missed seven games last season with a toe injury. He also missed six games in 2016 because of a hamstring tear. Green turns 31 on Wednesday and is trying to work out a contract extension with the Bengals. The two sides are far apart, according to the Cincinnati Enquirer’s Tyler Dragon.

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