The Ravens are concerned about starting cornerback Lardarius Webb's left knee injury and fear that he has a torn anterior cruciate ligament.
A magnetic resonance imaging exam will be conducted Monday to confirm the initial diagnosis.
Later, coach John Harbaugh confirmed the severity of Webb's injury.
"Lardarius Webb does not look good right now," Harbaugh said. "It's a potential ACL. We've got a problem there. We don't know for sure, but that's what it looks like right now."
Webb left the game in the first quarter and headed to the locker room for further examination.
Webb immediately grabbed his left knee and was on the ground in obvious pain. Trainers helped him off the field, and he barely put any weight on his leg.
The Ravens inserted Corey Graham as the nickel with Jimmy Smith taking Webb's place opposite Cary Williams.
Meanwhile, Pro Bowl middle linebacker Ray Lewis injured his right triceps in the fourth quarter and didn't finish the game.
Although Harbaugh said, "I don't think it's really bad," there was concern after the game that it's serious and he was set to get an MRI on his right arm.
Pro Bowl defensive tackle Haloti Ngata left the game in the second quarter with a sprained right knee. Ngata also aggravated a minor right shoulder injury.
He limped off the field and headed to the locker room for further examination from team doctor Leigh Ann Curl. He later returned and has recorded six tackles and a sack despite playing in obvious discomfort.
"Quite a bit," Ngata said when asked how much pain he was in. "I tried to fight through it. I thought I would finish. I didn't want to not finish. We had a good rotation going on."
Cornerback Jimmy Smith didn't finish the game because of a strained groin.
Cowboys rookie cornerback Morris Claiborne, a first-round draft pick, injured his left knee during Ravens wide receiver Torrey Smith's touchdown catch toward the end of the second quarter. Claiborne was helped off the field by trainers, walking very gingerly and not applying weight to his left leg.
The Ravens are already playing without outside linebacker Terrell Suggs, who's on the physically unable to perform list with a partially torn right Achilles tendon.
Webb tore the anterior cruciate ligament in his right knee as a rookie and had it surgically repaired by Dr. James Andrews.
Webb was signed to a $50 million contract extension last spring and is indisputably the Ravens' top cornerback.