The team's top pass-rushing end was clipped in the knee by a Jets player during the first quarter Friday and is walking around with crutches and a large brace.
Dunlap has endured injury issues every step of his Bengals career. He missed two preseason games and the first two regular-season games during his rookie year of 2010 due to a strained knee and was shelved the entire preseason last year with a foot injury.
If Dunlap is out four weeks, he would miss the opener at Baltimore and theoretically be able to return Week 2 against Cleveland. Lewis clarified the timetable can vary as time progresses.
“It's just a matter of how Carlos' body comes around,” Lewis said. “He's been two days of the new, diligent Carlos Dunlap. He's aiming to be ready, to prove that he's ready to go. He's in a race.”
For Dunlap, the frustration more comes from an offseason spent dedicated to preventing injury sidelining him and seeing that stolen away in the first game.
“Obviously you are frustrated when it happens," he said. "Probably was a little hard on myself, but my family helped pull me out of that. It's part of football.”
Dunlap moves on, and though he was unaware of the four-week prognosis given by Lewis, he owns a timetable of his own.
“A week faster than they tell me,” he said.
Other injuries cleared up: RB BenJarvus Green-Ellis (foot) will not play Thursday against Atlanta. Lewis doesn't see the injury as serious and expects to be held out of only one game. With Bernard Scott (hand) also out, that allows extended reps for prospects Aaron Brown and Dan Herron.
“It's a really deep position,” Lewis said. “You've got those other guys battling for some spots, so it's a great way to showcase them.”
Safety Taylor Mays suffered a possible concussion in the first quarter, but Lewis expected him to return to practice Monday, so he'll likely be on the field for Thursday's game.
Linebacker Rey Maualuga (knee sprain) will be held out of Thursday's game, but primarily as a precaution. Maualuga is believed to be fine and will more than likely return for the third preseason game against Green Bay.
Zimmer impressed with defense: Demanding defensive coordinator Mike Zimmer isn't easy to please, particularly in the preseason, but walked away happy with his team's 17-6 victory against the Jets.
“I thought we did well,” he said. “We looked kind of like I like to look. We covered for the most part fairly close. We rushed the passer good. We were good in our run fits. We tackled good. For the first time out, it was probably a little better than I thought it would be.”
Much better than last year when the Bengals were sliced up in a 34-3 loss at Detroit.
Replacement referee error: Cincinnati was called for illegally lining up over the center on a punt against the Jets, and it allowed New York a first down instead of change of possession.
After reviewing the film, Lewis recognized the replacement refs blew the call by not knowing the rule.
“They missed the call,” Lewis said. “Hopefully you don't have a call like that missed during the regular season, because that was an easy one. That wasn't a hard one to get right. It's a totally different rule than what they have in college football. We did exactly what we were allowed to do.”
Follow Paul Dehner Jr. for Bengals updates from training camp at @CBSSportsNFLCIN.