The NFC North race has tightened up, and the Detroit Lions now face a difficult road test.The Lions (6-2), who lead the division by 1 1/2 games over the streaking Minnesota Vikings, head west to face the Los Angeles Chargers (4-4) on Sunday.Detroit will be the much fresher team, as it comes off a bye week, while the Chargers earned a road win over the New York Jets on Monday night.The Lions could have their dynamic running back duo to probe Los Angeles’ suddenly stingy defense. David Montgomery, who hasn’t played since Oct. 15 due to a rib injury, has returned to practice. Montgomery, who leads the team with six rushing touchdowns, surpassed the 100-yard mark against the Green Bay Packers and Carolina Panthers before he was injured against the Tampa Bay Buccaneers.Rookie Jahmyr Gibbs had a combined 189 rushing and receiving yards in the Lions’ latest game, a 26-14 win over the Las Vegas Raiders on Oct. 30.”Both of those guys have been dangerous for them this season,” Chargers coach Brandon Staley said of Montgomery and Gibbs. “I think they really give them that one-two punch that you’re kind of looking for from that position. They both are weapons in the passing game as well, and I think that’s what makes them challenging to defend is that they both can contribute in the passing game.”Staley’s defense has allowed a total of 19 points over the past two games, victories over the Chicago Bears and the Jets.”We’ll have some things to try to attack them, certainly in the run game, and build off of that,” Lions coach Dan Campbell said. “But they’re playing pretty good football, particularly these last two games.”Detroit also can gouge opponents through the air, led by the combination of quarterback Jared Goff and wideout Amon-Ra St. Brown. The Lions’ top target has exceeded 100 receiving yards five times this season.Goff will have to dodge a Chargers pass rush that features Khalil Mack, Joey Bosa and Tuli Tuipulotu, who have combined for 19 1/2 sacks.”They’re able to generate some pressure,” Campbell said. “We’ve seen some good pressure players, too, up to this point. We just faced one before the bye in (Las Vegas’ Maxx) Crosby. I certainly like our tackles, our O-line, but we’re going to (need) a plan for those guys.”