Detroit Lions starting tight end Eric Ebron sustained what a teammate called a "devastating" injury on Saturday during the team's annual mock game.
Ebron had to be carted off the field after suffering an injury to his lower right leg, the Detroit Free Press reported.
The third-year tight end was injured on a running play and appeared to grab the back of his ankle before he was attended to by team trainers.
The NFL Network reported that Ebron hurt his Achilles, but Lions coach Jim Caldwell declined to comment on the nature of the injury later Saturday.
However, Matthew Mulligan, a backup tight end to Ebron, painted a gloomy picture of the injury after practice.
"It's devastating," Mulligan told the Free Press. "Anytime you see one of your guys go down, especially a guy you're so close with cause we're in the same room, it's awful and you feel for him because you know how much work guys put in.
"It's not just now, it's not just practice, it's not just training camp, it's all year round. So to have injuries and have things like that come up, it's a terrible situation."
Although Ebron has underachieved in his first two seasons with the Lions, the No. 10 overall draft pick's absence would present a huge void in Detroit's passing attack.
The Lions were expecting Ebron to become an integral part of the offense, particularly following the offseason retirement of perennial Pro Bowl wide receiver Calvin Johnson.
"For him it's frustrating, but it's another bump in the road that he'll overcome and a lot of people hate on him and give him a hard time but he has a very high ceiling," third-year linebacker Kyle Van Noy told the newspaper. "He's young. People forget that. He's really young, he still has a long career ahead of him and if he continue to grow each and every year like he has in the NFL he'll be fine."
Ebron, 23, appeared in 14 games last season, hauling in 47 receptions for 537 yards and five touchdowns. The former North Carolina product had a rather nondescript rookie campaign with only 25 catches and one TD in 12 games.