The Ravens entered Week 3 in pretty good shape with injuries, but that didn't last long in New England.
Left tackle Patrick Mekari exited with an ankle injury on Baltimore's second offensive drive, then veteran defenders Justin Houston (groin) and Michael Pierce (arm) went down later in the first half. Pierce was ruled out at halftime and Houston was ruled out midway through the third quarter.
After the game, Head Coach John Harbaugh said Houston suffered a minor strain.
"I don't know if it will be a week or not," Harbaugh said. "We'll see."
Pierce's injury could be more serious, however.
"We'll have to see tomorrow," Harbaugh said. "It's not definitive yet which way what it is exactly in terms of seriousness. A decision will have to be made on that."
The Ravens were already thin at outside linebacker with just Houston, Odafe Oweh and Malik Harrison as the only outside linebackers on the depth chart. The Ravens also activated Brandon Copeland from the practice squad.
Baltimore agreed to terms on a one-year deal with veteran Justin Pierre-Paul late this week but he won't be joining the team until Monday.
Pierce went down after Houston and walked off the field holding his arm. He's part of a deep defensive tackle rotation with Justin Madubuike, Broderick Washington and rookie Travis Jones, who is making his debut. Jones is behind Pierce on the depth chart.