PITTSBURGH -- The Pittsburgh Steelers added a significant name to their list of injured players Tuesday: Ben Roethlisberger.

Coach Mike Tomlin said the quarterback was dealing with a left pectoral injury, but said he didn't know how it happened. It wasn't publicly disclosed during postgame interviews with Tomlin or Roethlisberger.

"I don't know specifically when Ben got injured in game," Tomlin said. "I don't know that he does. You know, sometimes just in the midst of competition, adrenaline and so forth, you just don't know. Sometimes things just come up after."

Roethlisberger took just two sacks in the loss to the Las Vegas Raiders, but he was hit 10 times. Tomlin acknowledged it was too much for his 39-year-old quarterback and offered solutions that could keep every week from being a repeat.

"Yeah, he did," Tomlin said. "He took too many hits. We can run the ball better. We can get the ball out of his hand quicker. We can stay on schedule and not get behind the sticks and get in situations where the line of the game is so far that that that enhances the rush."

A week ago, Roethlisberger said he felt some of the soreness associated with live tackling after the first game, and he acknowledged it again after the second.

"I'm disappointed we lost the game, and I'm disappointed that I didn't play well enough to help us win the game," he said Sunday. "The bumps and bruises come with football."

The Steelers' injury issues, though, extend far beyond Roethlisberger. Four Steelers are dealing with groin injuries, including T.J. Watt, who exited the game in the first half. Fellow outside linebacker Alex Highsmith is also dealing with a groin injury that wasn't disclosed after the game. He was previously working through a groin injury late in training camp.

Devin Bush and Joe Haden also have groin injuries that kept them out of Sunday's game.

"I'm not making any drastic statements about the availability of any of these guys because of the degree of the injury changes, the prognosis," Tomlin said. "And the man himself changes the prognosis. We'll give guys an opportunity that are close enough to help the practice. We'll give them an opportunity to practice during the course of the week.

"And if they practice, we'll look at the quality of that practice or how much they practice and let that be a guide for us in terms of their potential participation. Some more established players can play on less prep than others. ... There are a lot of variables at play, but not overly concerned about it. This, you know, this is the tightrope that we walk week in and week out."

Nose tackle Tyson Alualu also went on injured reserve with an ankle fracture and had surgery for it Monday, Tomlin said. The Steelers promoted defensive lineman Henry Mondeaux from the practice squad to fill Alualu's spot.

Wide receiver Diontae Johnson injured his knee on the final play of Sunday's loss. Tomlin was vague, yet somewhat optimistic about his status.

"He's looking better, but not to be confused with great," Tomlin said. "We'll follow him and his health as we get through the week."

Even with so many injuries ahead of an AFC North meeting with the Cincinnati Bengals, Tomlin said the answers are "in-house."

"Thankfully in today's NFL, with the flexibility of practice squads and so forth, we have all the answers in-house. I'm not necessarily worried about the injury in terms of our expectations, in terms of our performance," he said. "We have a week to prepare with known issues. In-game injuries cause more problems than known issues like you're faced with here at the top of the week."

To help with the injury situation, the Steelers signed former first-rounder Taco Charlton to the practice squad Tuesday. Charlton spent two seasons in Dallas, one in Miami and one in Kansas City. He joins safety Karl Joseph as one of two former first-round picks on the Steelers' practice squad.