The 4-2 Carolina Panthers haven't lost a game since Kyle Allen replaced Cam Newton under center, but this offense will be faced with their biggest test of the season when they travel out west to take on the San Francisco 49ers.

While the 49ers' have an impressive offensive attack, their defense may be the real reason this team has yet to suffer a loss. No. 2 overall pick Nick Bosa has made an immediate impact, DeForest Buckner is continuing to dominate and linebacker Kwon Alexander has emerged into one of the best inside linebackers in the league. Despite all of this talent, they may also be facing their toughest challenge this season, as the Panthers possess a dual-threat weapon that has been hard to contain. 

Running back Christian McCaffrey currently ranks second in the NFL in yards from scrimmage with 923, and is tied for the most scrimmage touchdowns in the NFL with nine. He has 618 rushing yards and seven rushing touchdowns to go along with 305 receiving yards and two receiving touchdowns. He's just as effective as a receiver as he is a rusher, and the Panthers have been relying on him to win games all season.

This year has been so good to McCaffrey that the 23-year-old is starting to be compared to NFL legends. 

"He reminds me of Marshall Faulk," 49ers head coach Kyle Shanahan said of McCaffrey, via "He can beat you in the pass game, he can beat you in the run game. They're doing a great job on how to use him because they are using him as much as possible. You can tell he's a very smart player, extremely talented and that's why he's being mentioned with some of the best in the league this year."

In Faulk's first season with the St. Louis Rams back in 1999, he was at the center of Mike Martz's "Greatest Show on Turf." He recorded over 1,000 yards on the ground and over 1,000 yards through the air. In all, he racked up a then-NFL record 2,429 yards from scrimmage, which passed Barry Sanders' record of 2,358. The Rams ended up winning the Super Bowl, and Faulk won the NFL Offensive Player of the Year Award. 

Faulk kept up his production over the next few seasons, and the MVP award finally came his way in 2000. While he's one of the most electric offensive playmakers of all time, Faulk will be remembered for what he was as a dual-threat weapon. He became the first running back in NFL history to lead his team in receptions in five separate seasons. He's a big reason why NFL teams started to look to utilize their backs in the passing game. 

McCaffrey is doing what he can to advance the game like Faulk did. Just last year, the former Stanford standout recorded 107 receptions, the most made by a running back in a single season in NFL history. McCaffrey could up his MVP stock in a big way if he registers another impressive performance against the 49ers. Clearly, Shanahan and his team are not sleeping on him.