As he was dropping back to pass-block, he got tangled up with teammate Justin Britt, who was on the ground.
Fant, who was in line to start at left tackle, tweeted a message thanking fans for their support after he was carted off the field:
"We talked about the great year that he had this offseason and that it's going to take that same kind of application and fight and competitiveness and spirit to work his way back through this," Carroll said of Fant's recovery, according to Aron Yohannes of the team's official website.
The Seahawks had the lowest-rated offensive line in the NFL before Fant's injury, per Pro Football Focus. News that he will miss the season only stands to hurt a front five that "finished dead last a season ago in snap-adjusted run-blocking grade and snap-adjusted pass-blocking grade."
Rees Odhiambo is the most likely candidate to be installed as Seattle's new left tackle. However, Carroll could also pivot to left guard Luke Joeckel, who protected the blindside with the Jacksonville Jaguars after he was selected second overall in the 2013 draft.