Injuries always make football handicapping more of a challenge, and a few key injuries this past week will make the next few weeks particularly difficult when it comes to betting for or against some teams. The big challenge is not only to make sure that you are aware of the injuries that will affect the outcome of games, but that you are accurate in the amount of value you assign to the injury. Not taking an injury into consideration is a serious error, but overcompensating for an injury can be just as bad.

The first injury is one you have had to deal with already this year if you bet the NFL every week, and it may not be long lasting. Ben Roethlisberger went down in his game against Atlanta with a concussion and he missed the rest of the game. He was reportedly temporarily unconscious on the field. The injury itself isn't the end of the world - he has done well in the tests since and this concussion isn't anywhere close to as serious as the brain beating that Kansas City's Trent Green took. Where it does get sketchy, though, is that this is the second concussion he has had in four months (the first was caused by the car which tried to run him over). Two concussions close together are never a good thing at the best of times, and for a quarterback they can be a real problem. Ask Troy Aikman or Steve Young what happens when you start racking up the concussions.

As far as betting on the Steelers, however, this injury is probably the least concerning and least difficult to deal with. We now know that Roethlisberger practiced with the team on Thursday, which means that he will most likely start on Sunday. Bodog and others held off on posting a line in this game until they were comfortable that they had enough sources to make a solid line. The Steelers got a break, however, in that they are playing the lowly Raiders this week, so they are still nine point favorites and can be considered playable if you like them regardless of who takes the snaps. Even with Roethlisberger out the line could very well move away from the Raiders, and if he plays -- as it now looks like he will -- the Raiders will be very unattractive to the public.

The bigger quarterback issue to consider is Matt Hasselbeck. He went down with a knee injury and will miss three weeks. A quick look at the stat line of backup Seneca Wallace (14-25, 134 yards, 2 interceptions) shows you just how long that three weeks is going to be. With Shaun Alexander still out and only questionable for a return already, and the offense struggling to find an identity even before the injury, it's certainly hard to believe that the offense will be able to do a lot to help the defending NFC champs win. The line reflects this - anywhere that posted it on Sunday, before the severity of Hasselbeck's injury was known, listed Seattle as 2.5-point favorites when they were traveling to Kansas City. When word of the injury came out the line shifted immediately to make Seattle six point underdogs. Now Chiefs QB Damon Huard suffered a mystery groin injury in practice on Thursday. We'll have to see where this line goes by game time.

When it comes to handicapping games in which injuries are involved, you not only have to be aware of what impact the injuries will have on the outcome of the game, but you also have to consider the impact the injuries will have on the movement of the line. In a case where the injury occurred on Sunday, the line often won't be set until the extent of the injury is known, or it will be shifted quickly to account for the injury. Despite that, the public will often overcompensate and will move the line further away from the team with the injury. You need to be aware, then, of how the line is likely to move, and get in on the game quickly if it means getting a line you can live with. If you like the team without the injury, however, your patience could be rewarded with a better line once the public overreacts.

According to Bodog, not all injuries are created equally. Or at least bettors don't treat them equally. The public tends to overreact to injuries to running backs and quarterbacks, while not giving injuries to linemen or kickers enough due. The action also seems to react much more to a key offensive injury than it does to a key defensive injury. The Seahawks or Steelers lines will likely react more because of the Hasselbeck or Roethlisberger injuries, then, than the Giants line will despite the season ending injury to LaVar Arrington and Osi Umenyiora's hip flexor that will likely keep him out on Sunday.

The other challenge when compensating for an injury is to know when to stop compensating. San Diego presents a perfect example of this. When outside linebacker Steve Foley was shot a week before the season started, you had to be concerned about what would happen to the defense. His replacement, Shaun Phillips had played decently in two seasons, but he had never been relied on like he would be this year, and since his position is so key in a 3-4 defense, it was a bit of a worry for the team. Phillips came out in the first week and put up two sacks and three tackles, showing that he would be just fine. No more compensating. Now Phillips is out for a month and we again have to compensate for his absence and the inexperience of his replacement. Bettors seem only slightly worried about how the defense will react to his absence. Their line has tightened by a point, but they are still nine point favorites over the Rams.