The plan set forth by Bill Belichick on the eve of training camp seemed pretty simple, if noteworthy. Jimmy Garoppolo was the preparation priority this summer as he would start the first four games of the 2016 season before Tom Brady returned from his four-game Deflategate suspension to retake the starting job in New England.

But as the saying goes, man plans and God laughs. Of course some in Patriots Nation think Belichick is closer to the latter than the former.

While Belichick may have tried to project who would be playing quarterback each week this year as early as July 27, his plan has been thrown for a loop. Garoppolo left the second quarter of last Sunday's win over the Dolphins with what appeared to be a severe shoulder injury. Rookie third-round pick Jacoby Brissett came on in relief and held on for the win.

Rolling things forward a couple days, though, the situation is neither as clear as Belichick planned out nor as simple as it look from afar last Sunday evening. Garoppolo practiced on a limited basis this week, though New England did little more than glorified walkthroughs at Gillette Stadium.

Still, his status remains uncertain and Belichick indicated on Wednesday that he could be a game-time decision, even if he's officially listed as doubtful on the team's injury report.

Belichick also chose not to add a veteran quarterback to the roster despite reportedly working out both T.J. Yates and Sean Renfree.

So, barely 24 hours before a matchup with the undefeated Texans (2-0) on Thursday Night Football, the quarterback situation in New England is as uncertain as it has been in decades.

The door is left open for Garoppolo to play, even if the most likely scenario is for Brissett to make his first-career start. There is even the possibility that wide receiver Julian Edelman (a quarterback at Kent State) could be New England's backup heading into a battle with the J.J. Watt-led Houston defense.

Oh, and on the other side of the ball the Texans have a newcomer in their own right as big-money free agent addition Brock Osweiler looks to remain undefeated as Houston's starter while trying to improve on some lackluster early season numbers.

Quarterback is always at the center of attention in New England and really all of football. But which player in particular will be at the center of that attention - and under center against old friend Vince Wilfork and the Texans - isn't exactly clear.

Welcome to the 2016 Patriots, the season of the quarterbacks.

Beyond simply the quarterback story, here are few more keys to keep an eye on as two AFC playoff contenders get set to battle it out in Foxborough after a short week of preparation.

QB or not QB - The most likely scenario would appear to involve the third-round rookie Brissett having to start against Houston. But Belichick certainly seems to have liked the fact that there is a lot of uncertainty for Bill O'Brien and the Texans to deal with. At some point, though, New England has to send a player on the field to run the huddle, call a play and execute the offense. Whether that's Garoppolo nursing an injury to his throwing shoulder, Brissett or Edelman, it would seem Josh McDaniels will again earn his keep putting together an effective game plan. At least in terms of Garoppolo and Brissett, this feels like another week of trying to remain balanced and utilize a short passing game on offense. Brissett ran plays that limited his reads and decisions against Miami and that could continue against Houston. He's probably not ready for the entirety of the offense or a game plan that Brady or Garoppolo might run. But, coaches usually simplify things on a short week anyway. Regardless, the management of, and play from, the quarterback position will be the central storyline in this game from a Patriots perspective.

Game of chess - The uncertainty at quarterback only adds to what should be an intriguing war of sideline wits this week. O'Brien's staff is littered with former Belichick assistants and players. Romeo Crennel spent a lot of time learning from and helping Belichick. Same for Mike Vrabel. O'Brien and George Godsey clearly run an offense that has its roots in Foxborough. But the unknown of the offense New England will run without Brady, maybe without even Garoppolo, makes the Patriots that much more of an unknown. That could negate any advantage based in familiarity that Houston holds. What do the Patriots look like with a game plan designed for Brissett? New England's staff can barely know that, never mind ex-Belichick assistants working elsewhere. So maybe, just maybe, the uncertainty will be an advantage. Maybe.

GTFB on defense - The exact meaning of that acronym isn't family-friendly, but let's just say the Patriots secondary needs to avoid giving up big plays in this one, avoid letting Texans receivers get behind them. The secondary struggled, by its own admission, in the second half against Miami. That needs to improve this week against an offense that will take its chances down the field. Osweiler tries to make big plays through the air. He has a couple big-play receivers to do that with in DeAndre Hopkins and rookie Will Fuller, the latter averaging 23.4 yards per catch at this early point in his pro career. Malcolm Butler, Logan Ryan and Justin Coleman need to be better at cornerback. But the Devin  McCourty-led safeties need to improve as well. Taking away the big play will not only help New England's chances of winning, as would be the case in almost any game, but also take away what has been the biggest strength of the Texans offense to date.

Five-way rush - The word rush has a lot of meanings on a football field. All of those meanings are key in this Thursday night battle. LeGarrette Blount had one of his better days rushing in a Patriots uniform last week when the team needed him to run out the win on the Dolphins. Doing anything like that again, against a Texans team allowing nearly 5 yards an attempt on the ground, would be a huge boon for the offense regardless of the quarterback. The run defense for the Patriots has been inconsistent at times, though it was pretty solid against Miami. Lamar Miller has been shaky in the start to his Texans career, continuing that trend would be a nice first step for the New England defense. That would allow it to turn its attention to pass defense and dealing with the Houston big-play attack. Part of that plan of defense should be improvement from a pass rush that's been lackluster to open the year after setting pretty high hopes this summer. Jabaal Sheard, in particular, is a guy who would seem due to make some noise getting after the quarterback, while Chris Long can continue a pretty impressive start to his New England career. Finally, is how the Patriots deal with Houston's pass rush, regardless of who is at quarterback. New England's make-shift young line needs to at least be competitive against the likes of Watt and Jadeveon Clowney. Watt seems to be feeling better by the week after summer back surgery. That's a scary thought. Oh, and one final rush. This is an NFL Color Rush game, with the Patriots wearing all blue tops and bottoms. History has shown the Patriots to be 0-2 in a previous incarnation of a blue-on-blue uniform. Can they turn that around in the new-look Color Rush duds?

Prediction - Short weeks for Thursday night football usually favor the home team. Houston had to travel and had less time to prepare, with O'Brien joking that he had to sleep in his office. If the Patriots were seen as an unknown to open the year under Garoppolo, that's even more true with the potential of Brissett leading the offensive charge. The good news is that it feels like Rob Gronkowski might be ready for a return. That could mean a meeting of the two best non-QB players in the NFL at some point, the All-Pro tight end meeting the All-Pro defender in Watt. Sometimes, Thursday night brings some ugly play with players not performing their best in any area. This feels like a game that could lead to that, when all the various factors are considered. But a Belichick-coached team playing at home is still a Belichick-coached team playing at home. The defense, especially in the back end, seems like a group with something to prove after last week's dismal second half. Maybe the offensive line and Blount feel the same with some pressure to keep things rolling on the ground. The Patriots have a lot of talent and fight to go around. That will certainly be put to the test in this one, but it will also be enough to get the job done. Turnovers and special teams could be key. Penalties need to be cut down. Mistakes will be costly. But this feels like a game that could be somewhere in the range of a23-13 win for the Patriots. It may take a complementary effort with contributions in all three phases, but New England has the ability to get that done and remain undefeated while giving Houston its first loss of the new season. Belichick the teacher is victorious over his upstart pupil O'Brien.

What do you think of our keys? Let us know with a comment below!