The St. Louis Rams have allowed a 64.2 QB rating through four games this year—the lowest average QB rating in the league.
Chances are, even some of the more in-tuned NFL fans weren't aware of that statistic.
Their eight interceptions are second in the league—a total trailing only the Chicago Bears' 11.
The 4-0 Arizona Cardinals, well, they've been the talk of the NFL at the quarter pole; and those who weren't initially familiar with the stoutness of their defense have certainly been reminded over the past month.
Currently, opposing quarterbacks have combined to average a 74.3 QB rating against Ken Whisenhunt's secondary—the league's sixth-lowest average.
We can say with confidence that neither team boasts a dynamic passing offense, or anything resembling one, so it's obvious tonight's game will be won by the play of the defensive backs.
For the Rams, the free-agent addition of Cortland Finnegan has paid major dividends. He and controversial 2012 draftee Janoris Jenkins have formulated one of the most underrated and pesky cornerback duos in the NFC.
Finnegan has defended six passes and has three interceptions. Jenkins has four passes defended and an interception to go along with 20 total tackles.
Calvin Johnson reeled in six passes for 111 yards and Matthew Stafford threw for 355 yards in a Week 1 win over the Rams, but the Detroit Lions quarterback was intercepted three times.
In Week 2, Robert Griffin III was held to 206 yards through the air. Jay Cutler finished with a 58.7 QB rating in Week 3.
Russell Wilson was struggled mightily last week en route to a 160-yard, three-interception disaster.
Think Kevin Kolb will have a difficult time moving the football through the air tonight?
The Larry Fitzgerald and Cortland Finnegan battle is a premier matchup, one that'll be a major deciding factor.
Which team has the better cornerbacks/secondary?
Jenkins will likely matchup with Andre Roberts.
On the Cardinals' side, Patrick Peterson and William Gay have exceeded expectations early in 2012.
Sure, Ryan Tannehill went crazy for 431 passing yards on Arizona's secondary in Week 4, but in the other three games this season, Wes Welker's five-catch, 95-yard effort in Week 2 is the best day the Cardinals' defensive backfield has allowed to any pass-catcher.
Peterson is still learning the intricacies of playing the corner position in the NFL, but has the athleticism to compete with any wideout in the game.
He will likely draw the slippery Danny Amendola, a guy that will take plenty of snaps from the slot as well. Gay should get Brandon Gibson on the other side of the formation.
And we mustn't forget about Pro Bowl safety Adrian Wilson, one of the most intimidating safeties in football.
With loads of relatively overlooked secondary talent that has provided its respective club with early production, whichever unit has the stingier game locking down the opposing receiving corps will lead its team to victory.