The NFL season may only now be approaching the midway point, but tonight's matchup between the Indianapolis Colts and Tennessee Titans has major playoff implications.  Peyton Manning and Co. are a disappointing 3-3 on the sesaon and a loss could be the end of their postseason dreams.  Meanwhile Kerry Collins leads an undefeated Titans squad that is also sporting a perfect 6-0 ATS record.

These are the kind of games Monday Night Football was made for. The Indianapolis Colts (3-3 SU, 3-3 ATS) are in Nashville to face the Tennessee Titans (6-0 SU and ATS) in an AFC South matchup with major playoff implications – yes, even in Week 8.

The AFC has fallen into chaos this year. The NFL’s power conference is 11-15 SU against the NFC. The Colts are one of the problem teams, getting outscored 131-128 on the season and failing to establish any kind of rhythm. The Titans are the only winning team left in the AFC South – and winning is all they’ve done so far. They’re 4-point favorites on Monday night’s betting odds with a total of 40.

We’re at the time of year when the nights get a little chilly on the Cumberland Plateau. Temperatures at LP Field are expected to dip into the low 40s under clear skies with a fairly light breeze. The last time the Titans played at home, it was over 80 degrees on a warm Sunday afternoon against the Vikings in Week 4.

Perhaps anticipating some difficulty moving the ball with frozen fingers, the total has dropped from 42½ points at the open. The Colts have had trouble moving the ball in any weather. Their troubles go beyond an injury-plagued offensive line – the latest focus is on the health of Peyton Manning, who the Colts confirmed had a staph infection in his knee this summer after initially going under the knife to repair an inflamed bursa sac.

The Colts offensive line has been abysmal at run blocking, but Manning has only been sacked nine times this year, so he can’t sue for lack of protection. That makes it more likely that Manning’s second knee surgery – originally hidden from the media – is behind his worst season since his 1998 rookie campaign. Manning had 31 touchdown throws in each of the last two seasons; this year, he’s on pace for 21.

Worse, the battered state of the Indianapolis running game throws the entire offense off balance. Joseph Addai (3.5 yards per carry) is out with a hamstring injury, leaving Dominic Rhodes (3.4 yards) as the primary ball carrier for the third straight week. Chad Simpson was signed off the practice squad earlier this month to be the No. 2 tailback while Addai heals. The Colts are already down from fourth to twelfth in rushing efficiency this year; having Addai out for one more week will not help.

This skeleton crew has to perform on Monday night against Albert Haynesworth and the fearsome Titans defense. The most points Tennessee has allowed this year is 17, which was in the aforementioned Vikings game. It’s true that this defense hasn’t really been tested, but even when adjusting for competition level, Tennessee ranks No. 1 in the league against the pass and No. 6 against the run.

Unless the Titans defense returns a fumble or two into the end zone, their dominance in this matchup is the key to the bank for the under. The weather helps; so does Tennessee’s smashmouth running combo of Chris Johnson and LenDale White, who carry the ball a combined 30 times per game. However, the Colts defense has been such a wreck without safety Bob Sanders that the over is 3-1 in their past four games.

Tennessee could easily end up dominating this game on both sides of the ball. Veteran QB Kerry Collins has taken a management role in the Titans backfield, throwing just three interceptions thus far and taking just one sack. It helps having former Colts guard Jake Scott on the O-line; they’ll confront an Indianapolis front seven that has forced only 10 sacks and is constantly springing leaks against the run. Conveniently enough, the over is also 3-1 in Tennessee’s past four games.

The usual suspects at ESPN will be on hand at 8:30 p.m. Eastern to televise the game. The Titans are 4-0 ATS against the Colts since 2006, and the under is on a six-game streak when these two foes meet.