The NFL's win-now mentality and the brutal reality of injuries has forced head coaches to start backup quarterbacks.

Five teams in Week 8 will turn to a quarterback who wasn't their opening-day starter. Each team has its reason why it needed to make the change, but two (Browns and Jaguars) are likely making long-term decisions because their first-stringer never lived up to their first-round billing.

In fact, a sixth team should be included on this list as the Vikings already made the bold decision to go with newly arrived Josh Freeman instead of 2011 first-round pick Christian Ponder. Since Freeman is suffering from concussion-like symptoms, Ponder will get another opportunity to show head coach Leslie Frazier that he deserves the job.

Also not among this list are two teams on a bye, who have quarterback issues for separate reasons.

Bears quarterback Jay Cutler has been ruled out for at least four weeks because of a groin tear. Eleven-year veteran Josh McCown now must operate Marc Trestman's stretch-the-field offense.

In Houston, head coach Gary Kubiak said Matt Schaub will get the start in Week 9. While that might be the politically correct answer so the team isn't a talking point during its bye, undrafted free agent Case Keenum will likely get the start. Keenum played above expectations in Week 7 against the Chiefs and didn't make the back-breaking mistake throws which Schaub has been known to make.

With that said, let's get into which teams will start a backup instead of their former first-round picks and opening day starters.

Tampa Bay Buccaneers

Opening day starter: Josh Freeman -- The highly publicized breakup between the Bucs and Freeman ended when they released him in October. Freeman found a new home in Minnesota, but it's probably only temporary as he'll be a free agent after this season.

Week 8 starter: Mike Glennon -- The rookie quarterback will make his first primetime start on Thursday against the Carolina Panthers. Glennon, who was selected in the third round of the 2013 NFL Draft, has a stiff challenge against one of the most opportunistic defenses in the league. He'll also be without his starting running back Doug Martin. A steady diet of rookie Mike James could be in the cards.

Cleveland Browns Opening day starter: Brandon Weeden -- The new Browns regime are officially saying sayonara to the Brandon Weeden era. It has grown difficult to watch Weeden in Cleveland play as he's coming off a performance in which he completed just 40 percent of his passes. Oh yeah, that was against the Packers, who were without three of their starting linebackers. Weeden is inaccurate, makes bad decisions and doesn't properly anticipate defensive coverages. They tried making the switch by giving Brian Hoyer the gig in Week 3, but he was knocked out for the season with a torn ACL against the Bills.

Week 8 starter: Jason Campbell -- Offensive coordinator Norv Turner would prefer to have a gunslinger operating his offense, but at this point the steady hand of Campbell will have to do. Campbell made two starts in Chicago last season and has never had an opportunity to succeed in a stable situation. It's not going to get any easier as the Browns play the Chiefs at Arrowhead Stadium. At least the team has more confidence in him than 43-year-old Jeff Garcia.

Buffalo Bills: Opening day starter: EJ Manuel -- The Bills' prized rookie quarterback continues to rehab a knee injury which will likely keep him out another 4-6 weeks.

Week 8 starter: Thad Lewis -- The journeyman quarterback started this season on the practice squad. This week, he'll be making his third start for the Bills. Lewis, 25, has filled in admirably since head coach Doug Marrone made the decision to go with him over undrafted free agent Jeff Tuel. Offensive coordinator Nathaniel Hackett has designed the game plan around Lewis' skill set, employing the short-passing game. It will be a whole new challenge as they play in the noisy environment of the Superdome against the Saints.

Jacksonville Jaguars Opening day starter: Blaine Gabbert -- Like the Browns, the Jaguars have seen enough. Although Gabbert suffered a hamstring injury, he has been cleared to play for weeks. The Jags coaching staff still believes Chad Henne gives them a better opportunity to win.

Week 8 starter: Chad Henne -- New head coach Gus Bradley and general manager David Caldwell have been very supportive publicly of Gabbert since they inherited the responsibilities last January. This move makes it clear that they are moving on without him. Henne surely isn't in the long-term plans for the Jaguars and is likely a stopgap between now and when they spend a first-round pick on a QB in May. For Henne, it will be his duty to put some solid play on tape so that he'll have a market for his services when he becomes a free agent after the season.

St. Louis Rams Opening day starter: Sam Bradford -- The 2008 No. 1 overall pick is sidelined for the season with a torn ACL in his left knee. Bradford's longterm future is also uncertain, although his contract runs through the 2015 season. This was a very important season for him moving forward with the organization.

Week 8 starter: Kellen Clemens -- Everyone meets Kellen Clemens' name with a proverbial eye roll. While Clemens doesn't have a lot of starting experience, he's been in the league for eight seasons and is in his third with the Rams. It's clear that he's an emergency plan and offensive coordinator Josh McDaniels will have to get creative with him against the Seattle Seahawks on Monday Night Football. Good luck with that.

The original article can be found at FOXSports.com: Opening-day starters dropping quickly.