This Sunday's trip to Pittsburgh was supposed to be a measuring stick game for the Patriots.

It was supposed to be a battle of future Hall of Fame quarterbacks leading elite offenses.

It was supposed to be Tom Brady (four Super Bowl rings) and his depth of weapons against Ben Roethlisberger (two rings) and his All-Pro playmakers.

But, Big Ben's left knee injury suffered in last weekend's loss in Miami - and a the quarterback's Monday surgery that could reportedly sideline him for as long as six weeks - has sucked the hype and shootout possibilities from this AFC battle.

While it still could very well be a preview of a potential playoff matchup between these two longtime conference pace setters, some of the challenge and mettle-testing meat has been removed from the meeting.

New England is riding a two-game winning streak since Brady's return, a couple 30-point performances as the Patriots passing attack rounds into full form.

That will be the challenge facing the Steelers on Sunday at Heinz Field. It's a major challenge for a suspect and banged-up Pittsburgh defense. It's also a challenge in terms of trying to keep pace for inexperienced backup quarterback Landry Jones.

While it may not quite be the marquee game it appeared when the schedule game out, here are a few keys to Sunday's battle between two teams hoping to be fighting for a spot in the Super Bowl come January.

Air we go again!- Brady has two impressive performances since returning from his suspension, including six touchdowns and no interceptions for a combined 135.5 passer rating. He also has a combined 113.4 passer rating in eight previous career regular season meetings with Pittsburgh, with 22 touchdowns and just three interceptions, no picks in the last five meetings in the series. Oh, and Rob Gronkowski is coming off consecutive 100-yard days as he prepares for a Steelers team he's burned for 400 yards and seven touchdowns in four career games, including a pair of three-score performances. That is what faces the Steelers 30th ranked pass defense on Sunday. Brady and Co. should be able to spread the Pittsburgh pass defense out to throw early and often. They struggle to cover. They have just eight sacks all year. And they don't' have a single interception from the secondary. All signs point to a Brady-led passing game field day for the Patriots at Heinz Field. Good luck to Jones trying to keep up.

Third and improvement - The biggest weakness of the Patriots defense has been on third down. While the unit ranks No. 2 in the NFL in points allowed and a respectable 13th in yards, the group is a lowly 27th on third downs. That's not nearly good enough and the type of number that will lead to a loss sooner or later. It's been a major talking point this week in New England by players and coaches alike. Pittsburgh has been good on third down offense - fifth in the league - but that was with Big Ben. When a Bill Belichick-coached team openly emphasizes something more often than not it shows great improvement in that area. Facing a backup quarterback as limited as Jones should help make improvement on third down defense an achievable goal this week.

Stay with the stars - There is no question that Antonio Brown and Le'Veon Bell are two of the best players at their positions in the league. Brown leads the Steelers with 41 catches for 486 yards with five touchdowns. Bell is averaging 5.5 yards per carry since returning from his three-game suspension to open the year while already piling up 20 catches to tie for second most on the team. Asked about Bell's abilities, Belichick interrupted to say, "oh my god." But as great and potentially scary as Brown and Bell are, they are beholden to the unproven Jones to get them the ball and keep the offense moving. The Patriots will clearly target keeping Brown from making big plays, slowing Bell on the ground and tackling the back when he gets the ball through the air. Dont'a Hightower is fully healthy and should be up to the Bell task, especially if he gets his linebacker cohort Jamie Collins back from a hip injury. If the Steelers are to pull off what would now be an upset with Jones under center, Pittsburgh will probably need to get a big day from its star playmakers. 

Free pass - The Patriots have yet to throw an interception this season in six games with three different quarterbacks. The Steelers have notched just three interceptions in six games, none from the back end of the defense. In many ways that means it's a clear strength vs. weakness on Sunday. If New England can continue to play clean football on offense that takes away one of the limited chances the Steelers have to try to level an uneven playing field.

Line up - The Patriots offensive line has been a concern for years. The group has been up and down at times this season. It's coming off more of a down effort last week against the Bengals. Early and pretty consistent pressure saw the overall offense spinning its wheels before pulling away late. The Steelers don't have nearly the same front that Cincy does. Cameron Heyward missed practice all week and is out, meaning his team-high three sacks will not be a concern. Pittsburgh still uses some of the blitz-zone concepts they've been known for. Rookie defensive tackle Javon Hargrave is an athletic player who could challenge the young interior of the New England line. This should be a week that the Patriots line takes a step forward and shows improvement against an undermanned front. If not, that would crack the door for the Steelers to potentially frustrate Brady. It's unlikely, but it's one of the only chances the Steelers have.

Prediction - The bottom line is that the Steelers are a team whose success is based on offensive output and the key to the offense is out of action. Without Big Ben the Steelers are not the same team, not even close. Belichick talked this week about Jones being capable of getting the ball to Bell, Brown and others to allow the playmakers to do the work. That's debatable. What's not debatable is that the Patriots passing attack is rolling and among the most consistent in the game right now. They should be able to roll onto the field and score 30 points against almost any foe, especially one with a pass defense that's as bad as Pittsburgh's. Oh, you can also run on the Steelers, as Miami showed in a big way last week. The Patriots proved they could win without Brady earlier in the year, but such success is much easier said than done. New England had a better backup and a much better coach to pull that off. Mike Tomlin is overmatched by Belichick. Brady, Gronkowski and the rest should overmatch the Steelers to the tune of a blowout win, maybe 42-13, that will leave those waving the Terrible Towels feeling, well, terrible. Without Big Ben the Patriots have a bigtime advantage in this one and don't appear poised to make the mistakes it would likely take for Pittsburgh to have a chance.

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