DAYTON, Ohio (AP) — Near the end of a festive afternoon commemorating the NFL's centennial season, the Cincinnati Bengals watched A.J. Green get carted off the field with an injury that left the receiver distraught.

"You never want to see that," quarterback Andy Dalton said. "It's unfortunate."

One practice into coach Zac Taylor's inaugural season, the last-place Bengals saw their most indispensable player crumple on the field. Green ran a deep sideline pattern during a 7-on-7 drill. Cornerback Dre Kirkpatrick bumped him as he knocked away the pass, and Green appeared to land awkwardly on the left foot.

He limped a few steps, crouched, limped a few more and then appeared to grab his mouth guard, flinging it to the ground. He sat down and trainers removed his left sock and examined the foot and ankle. Green was helped to the bench, which he angrily slammed with his hand. He buried his head in his arms as he was taken off the sideline on a cart for an exam.

Taylor had no information about the severity of the injury when practice ended. Kirkpatrick also was seen by a trainer.

"You don't want to assume anything, but I think that we'll be OK," Taylor said, adding, "I don't know; I shouldn't speculate on anything."

The practice was held at Welcome Stadium, an hour north of Cincinnati, as part of the league's celebration of its 100th season. What's considered the first game in NFL history was played in Dayton in 1920. A main attraction for the crowd of approximately 7,500 was watching Dalton and Green connect again.

Dalton missed the last five games last season with a torn thumb ligament. Green missed more than half the season with an injured big toe on his right foot that required surgery. When players reported for the start of camp on Friday, Green was upbeat about his condition.

"My body feels great, my legs feel great," Green said Friday. "I started working out in February. I took a couple days off here and there, but it was just getting my toe right, getting my body back to where I need to be."

Green had been limited in offseason workouts as the Bengals went easy with their best receiver. Less than an hour into their first practice, he was gone again.

"I hadn't gotten a chance to see A.J. much," Taylor said. "I saw him one day in the spring time, and he was coming back off the toe injury. He was on pace to recover and I felt like he had a good summer. Sometimes like today, freak things happen, but we'll find out more about it a little bit later."

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