Neither, though, will have any impact on Sunday's rematch between the AFC's top teams in the Lone Star State.
Lewis recorded a team-high seven tackles and Webb intercepted two passes as Baltimore beat Houston 20-13 on Jan. 15 to advance to the conference championship game.
The Ravens' defense will look much different in this contest, however, after Lewis (torn right triceps) and Webb (torn left ACL) both suffered serious injuries in last week's 31-29 win over Dallas.
Baltimore (5-1) also has been without reigning defensive player of the year Terrell Suggs as he recovers from a right Achilles' tear suffered in the offseason. Suggs was removed from the physically unable to perform list and practiced for the first time Wednesday, and hasn't ruled out the possibility of making his debut Sunday.
That seems far-fetched, though, considering he probably won't be in game shape and a quick return could push back his recovery.
"There no plan in place," the five-time Pro Bowl linebacker said. "I've got to take it day by day. Come Sunday I may or may not be out there.''
Like Suggs, Webb also tore his right ACL, in 2009. The 27-year-old defensive back will likely recover and return next season, but the future isn't as certain for the 37-year-old Lewis.
With an enshrinement in Canton awaiting, the aging linebacker will have to decide if he plans to pursue another Super Bowl title next season. Lewis was put on injured reserve Wednesday, though Baltimore placed a "designated to return" tag on him in case he's able to play.
It doesn't seem likely, however.
"That's for Ray to speak on," Harbaugh said of Lewis' future. "When you look at his situation and what he's accomplished, and what he was hoping to accomplish this year, he's going to have to accomplish those things in different ways because that's the way it's gone. He puts his faith in providence. That's where he's going to go with that.''
With key defenders missing, the Ravens' task of slowing down Arian Foster may have become more difficult. Baltimore gave up 481 total yards and a franchise-record 227 on the ground versus the Cowboys.
Foster, who ran for 132 yards and a touchdown versus the Ravens in the playoffs, will be looking to bounce back after rushing for a season-low 29 yards on 17 carries Sunday as Houston (5-1) fell 42-24 to Green Bay. He scored on a pair of one-yard runs, but the Texans managed only 90 yards on the ground, marking the third time they've been held to 95 or fewer.
"The end result is we're not running the ball very good at all,'' coach Gary Kubiak said. "It's not going to change how we believe and what we think we have to do to win, we've just got to look really hard at it and hopefully change it this week.''
While the offense may have its issues, the defense will be out to prove last week's dismal performance was a fluke. Houston's defense, which entered the week ranked third in total yards (275.6 per game) and fourth in scoring (14.6), allowed 427 total yards as Aaron Rodgers picked apart the secondary for six touchdowns.
"It's a humbling game,'' said Kubiak, whose team is tied with Baltimore for the conference's best record. "You play a lot of football and you're going to have some highs and lows. That's the first big low of the year. We've got other challenges coming our way, so how we handle those type of things will have a lot to do with what we are when it's all said and done. It's a big disappointment, but we've got to move on.''
The Texans have lost all six meetings with the Ravens, and that streak may continue if the defense can't rebound to slow down Baltimore's offense, led by Joe Flacco and Ray Rice.
Flacco finished 17 for 26 for 234 yards and a touchdown, and Rice added two scores rushing Sunday versus Dallas for an offense that ranks second in the AFC averaging 385.0 yards per game.
"There have been many, many times where we've won because our defense has carried a heavy, heavy burden over the years,'' Harbaugh said. "For our offense to carry some of that burden ... is a great thing."
Baltimore's defense didn't have to face Matt Schaub in January after he suffered a Lisfranc injury in his right foot earlier last season, but he'll be under center Sunday.
Schaub, though, struggled against the Packers, tossing two interceptions while failing to throw a touchdown pass for the first time in four games. He's completed 52.5 percent of his passes in two career starts versus the Ravens.