ALAMEDA, Calif. -- After a season opener when just about everything went wrong, the Oakland Raiders finally got a piece of positive news.

Quarterback Derek Carr's injured throwing hand that knocked him out of the game Sunday is not as serious as originally feared, and the Raiders are hopeful Carr will be able to play this week against Baltimore.

An MRI on Monday showed that Carr only had a bruise on his right hand. Carr even showed coach Jack Del Rio that he was able to squeeze a ball in a positive sign that he should be able to practice this week.

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"He was feeling good about it, feeling a lot better with the swelling having gone down quite a bit," Del Rio said.

The Raiders are confident enough that Carr can play this week that they have no plans to sign a third quarterback to the active roster.

Carr hurt his hand when he tried to stiff-arm Adam Jones on a scramble late in the second quarter. He was replaced by Matt McGloin after that, and the Raiders lost 33-13 to the Bengals.

"Using his throwing hand to become a straight-arm tool, we would probably not ask him to repeat that," Del Rio said.

Carr, who made all 16 starts as a rookie, struggled before the injury, going 7 of 12 for 61 yards.

Carr was not the only Raiders starter to leave the game with an injury. Safety Nate Allen went down in the first quarter with a knee injury, fellow safety Charles Woodson hurt his shoulder on a garbage-time drive in the fourth quarter and defensive tackle Justin Ellis left early with an ankle injury.

Del Rio said Allen would miss time but could be back later this season. Del Rio had no results on Woodson's MRI, and Ellis' injury is not believed to be serious.

The direst situation is at safety, where the only healthy bodies are Larry Asante and recently acquired Keenan Lambert. Woodson and Allen, with more than 300 career starts, were expected to help cover up for an inexperienced cornerback group that struggled at times on Sunday.

Asante has started just two games since entering the league in 2010, and Lambert played just two defensive snaps in his debut as an undrafted rookie out of Norfolk State.

Del Rio said the team could add another safety this week.

Ellis was replaced mostly by Stacy McGee, who struggled Sunday in his most extensive playing time since his rookie year in 2013.

Few players fared well in the opener as the Raiders fell behind 33-0 after three quarters and didn't even run a play in Bengals' territory until the fourth quarter.

"Bottom line is we expected to do better," Del Rio said. "Whether you do better or not, this is a day you kind of acknowledge what went wrong or acknowledge what went right. You make your corrections, you learn from the experience you had and then you go forward."

NOTES: Del Rio was upset after looking at the film that Jones was not penalized more harshly for ripping Amari Cooper's helmet off and slamming his head against it at the end of a long run. "It was clearly way over the line," Del Rio said. "I understand now why our offensive lineman went down there and took issue with it. I respect that. I really don't understand how that was missed." ... Del Rio was pleased with what he saw from Aldon Smith, who got 29 snaps two days after signing with the team. "You can see he has obvious talent," he said.