The Seattle Seahawks were able to upset the San Francisco 49ers on Monday night even though one of their main offensive weapons — wide receiver Tyler Lockett — was not on the field for the overtime period. Lockett fielded the final kickoff of regulation and took a knee but then didn’t return for the extra session, and afterward Coach Pete Carroll said he had been taken to the hospital with a “really bad” lower leg contusion.

“I think there was a lot of swelling. The contusion caused a lot of swelling right away and they’ve got stuff … there [are] concerns about that so they’ve got to make sure,” Carroll said. “There’s a compartment element in this so they’ve got to make sure and just got to take care of him. And we’re ahead of it so we should be in good shape.”

Compartment syndrome is a rare but potentially dangerous condition in which pressure builds to extreme levels in a limb after it undergoes some sort of trauma, either from a big hit or simple exercise. Quick medical care is crucial in treating compartment syndrome, and Carroll said the team had done all the right things with Lockett.

“It’ll be okay, but it’s a pretty severe situation for right now,” he said.

ESPN’s Adam Schefter reported Tuesday morning that Lockett had spent the night in a Bay Area hospital, which turned out to be mostly a precaution. NFL Network’s Tom Pelissero reported Tuesday that it was his understanding that Lockett’s injury was simply “a real bad bruise that swelled a lot. Lockett did not need to undergo surgery."

In his fifth NFL season, Lockett has become a key cog in the Seahawks’ offense with a career-high 59 receptions and 85.2 receiving yards per game, nearly 25 more than his previous career best in that statistic. His absence in overtime on Monday was noted by the team’s coach.

“You could tell not having [Lockett] out there, we looked different,” Carroll said. “We need him back.”

The Seahawks have a bye in Week 11 before returning on Nov. 24 to face the Eagles in Philadelphia on “Sunday Night Football.”

Read more: