Joseph Ossai stood there is front of the media, while Bengals teammate B.J. Hill stood by for support, and talked about the mistake Sunday night that clearly was haunting him.

The Kansas City Chiefs were driving for a potential winning field goal in the AFC championship game when Ossai, a second-year pro, gave chase to scrambling Patrick Mahomes. Both were running at full speed when the All-Pro quarterback made it to the Cincinnati sideline, where Ossai gave a push from behind the sent Mahomes sprawling to the ground.

Penalty flags flew and Ossai knew immediately what he had done.

The 15-yard penalty for a late hit was enough to give Harrison Butker a field-goal chance, and the Chiefs’ big-legged kicker barely coaxed the ball over the crossbar, giving Kansas City a 23-20 victory and a berth in the Super Bowl.

“I was just in full chase mode and pushing to maybe get him going backwards, because I knew he was going for the sideline, so make him go backwards and get that clock running,” Ossai said. “I didn’t know how far out of bounds we were.”

It was enough that the flag was indisputable.

Making things worse, Ossai lay in a heap on the sideline as Mahomes trotted back to the field. He wound up hurting his right knee on the play, and an MRI exam is due Monday to determine the nature and extent of the injury.

“I’ve just got to learn from experience and know not to get close to that quarterback when he’s close to the sideline,” said Ossai, who had played well up to the last minute of the game, and bravely answered questions from reporters afterward.

“If there’s anything that could possibly cause a penalty in the dire situation like that,” he said, “I’ve got to do better.”

Not everyone on the Cincinnati sideline was supportive after Ossai’s mistake. TV cameras caught linebacker Germaine Pratt asking with an expletive why he was even near Mahomes at that point in the game. But most of the Bengals were ready to stand by Ossai’s side, even batting away questions that they didn’t like in the postgame locker room.

The Associated Press contributed to this report.