Eifert suffered a broken ankle and is expected to undergo surgery, a source told ESPN's Adam Schefter.
The Bengals had tried to keep Eifert healthy by limiting his snaps in games this season, but he came down awkwardly on his right leg after catching a pass and being tackled by Falcons linebacker De'Vondre Campbell early in the third quarter. His leg went out at a sideways angle as he came down, and it was immediately clear that the injury was a serious one.
Eifert grabbed his helmet and started banging his hand on the ground, trying to get the attention of athletic trainers, who quickly ran to his side. Eifert was fitted with an air cast and placed on a stretcher before he was carted off the field.
Eifert appeared to have tears in his eyes as he gave a slight wave to the crowd as he left the field. The injury likely signaled another shortened season for him. Eifert has been rehabbing various injuries since the 2016 season; he has played in 14 games over the past three years.
Eifert injured his ankle in the 2015 Pro Bowl, and his debut in 2016 was delayed by a back injury. His 2016 and 2017 seasons ended with back surgeries. He also missed all of the 2014 season after injuring his elbow in the season opener.
Eifert tweeted Sunday evening that "if I've learned anything from before it's not a time for self pity and negativity."
Things were looking up for Eifert this year after he was able to fully participate in training camp, and things were starting to click for him regarding his role in the offense last week, when he caught six passes for 74 yards against the Panthers. Eifert had 4 catches for 38 yards and 1 touchdown against the Falcons before he went down with the injury.