Heading into their home opener last week, the Detroit Lions were riding a wave of confidence and praise.They were coming off a spirited road win over reigning Super Bowl champion Kansas City on national TV in the season opener. The euphoria died down quickly last Sunday.Following a humbling 37-31 overtime loss to the Seattle Seahawks, when several key players were injured, the Lions look vulnerable again. They will try to bounce back during a visit from the surprising Atlanta Falcons on Sunday.Lions head coach Dan Campbell believes some adversity could be a blessing.”We’re back to reality, we’re back in the mud,” Campbell said. “It’s doom and gloom outside of this building, in this world. Man, let’s just hunker down and go to work. … Challenge accepted.”The task will be much more challenging after two defensive starters, safety C.J. Gardner-Johnson (torn pectoral muscle) and defensive end James Houston (ankle fracture), were placed on the injured list.Two of their top offensive playmakers, running back David Montgomery (thigh) and wide receiver Amon-Ra St. Brown (toe), did not practice Wednesday.Tracy Walker, who missed most of last season with an Achilles injury, will step in for Gardner-Johnson.”We’re fortunate to have depth at a number of areas and one of them is at that position,” Campbell said. “Having a guy like Tracy, someone who we’ve got a lot of faith in, a lot of trust in, that alleviates a lot of pressure and stress for us.”Lions quarterback Jared Goff had the third-longest streak in NFL history without an interception snapped by the Seahawks’ Tre Brown, who returned the second-half interception for a touchdown. Otherwise, Goff was sharp with 323 yards passing and three touchdowns.”He’s played at a high level for a long time,” Falcons coach Arthur Smith said. “Been in a lot of big games. Good player, live arm. That’s what people loved about him coming out (of college). I always love when the guy’s a No. 1 pick and they act like he’s some kind of reclamation project. This guy’s a (darn) good player.”The matchup Sunday will feature the top two running backs chosen in the draft. Atlanta’s Bijan Robinson, the No. 8 overall pick, rushed for 124 yards in the Falcons’ 25-24 win over the Green Bay Packers last Sunday. He also has 10 receptions in his first two games.