(Sports Network) - First, folks weren't sure if New England Patriots Matt Cassel was suited to be the backup to Tom Brady.

Then, when Brady was knocked out for the year with a knee injury in Week 1 of the 2008 season, they were skeptical about whether he would perform well as the starter.

Two weeks ago, when Cassel threw for 400 yards and played extremely well in an overtime loss to the Jets, league observers wondered if he would ever be able to follow it up.

And now, one Sunday after Cassel became the fifth quarterback since the AFL- NFL merger to post back-to-back 400-yard games, the masses are certainly not convinced he'll be able to do something similar against the NFL's best defense.

The Pittsburgh Steelers will be the opponent for Cassel and the Pats in Week 13 at Gillette Stadium, and the challenge will be the biggest of the quarterback's surprisingly strong season to date.

The Steelers rank No. 1 in the NFL in total defense (235.4 yards per game), scoring defense (14.5 points per game), passing defense (168.8 yards per game), rushing defense (66.5 yards per game), yards allowed per rush (2.9), touchdowns allowed (15), and rushes allowed of 20 yards or longer (1).

Mike Tomlin's team is also 8-3 after last Thursday's 27-10 win over the Cincinnati Bengals, good for a one-game lead over the second-place Ravens in the AFC North.

In less firm control of their playoff fate are Cassel and the Patriots, even after last week's statement-making 48-28 win at Miami. New England comes into Week 13 a game back of the Jets in the AFC East, and also on the outside looking in on the Wild Card race.

A win on Sunday would be almost certain to improve that standing, and would also provide further evidence that Cassel is indeed ready for his close-up.

The former backup to Carson Palmer and Matt Leinart is a combined 60-of-94 with 815 yards, six touchdowns, and just one interception in his past two games, posting passer ratings of better than 100 in both contests and also rushing for 76 yards over that span.

In the Miami win, Cassel joined Dan Fouts, Dan Marino, Phil Simms and ex-Titan Billy Volek as the only players since 1970 to record consecutive 400-yard passing days.

SERIES HISTORY

The Steelers have a 12-7 edge in their all-time regular season series with the Patriots, but have lost two consecutive regular season games to New England including a 34-13 rout at Gillette Stadium in Week 14 of last season. The Steelers last defeated the Pats in 2004, at Heinz Field against a then-6-0 New England team. Pittsburgh is 0-2 in New England since last winning there in 1997.

The teams have also met in the playoffs four times since 1996, with the Patriots winning a 1996 AFC Divisional Playoff (28-3), the Steelers returning the favor with a victory in a 1997 AFC Divisional Playoff (7-6), and New England prevailing in the 2001 (24-17) and 2004 (41-27) AFC Championships. The 1997, 2001, and 2004 meetings were all played in Pittsburgh.

Patriots head coach Bill Belichick has a 8-9 mark against the Steelers, including 5-1 since coming to New England. Pittsburgh's Tomlin is 0-1 against both Belichick and the Patriots as a head coach.

WHEN THE STEELERS HAVE THE BALL

The run-first Pittsburgh offense heads into yet another game facing a question mark about oft-injured running back Willie Parker (485 rushing yards, 4 TD), who sustained a knee injury against the Bengals last Thursday and is regarded as questionable for New England. Parker has suited up just three times in Pittsburgh's last eight games, meaning backup Mewelde Moore (432 rushing yards, 31 receptions, 6 TD) is more than familiar with the role of lead back. Moore carried 15 times for 56 yards after Parker left the lineup against the Bengals, also catching four passes for 41 yards out of the backfield. Gary Russell (48 rushing yards, 1 TD) would be the change-of-pace back if Moore is Sunday's starter. The key to the Pittsburgh passing game is the ability of a poor pass-blocking offensive line to keep quarterback Ben Roethlisberger upright. When "Big Ben" has time to throw, wideouts Hines Ward (54 receptions, 5 TD), Santonio Holmes (39 receptions, 2 TD), and tight end Heath Miller (25 receptions, 2 TD) are the primary beneficiaries. Roethlisberger experienced a rare sack-less outing against Cincinnati last time out, allowing him to connect with Holmes for five balls and 84 yards, and Miller four times for 44 yards with a touchdown. The Steelers o-line gave up 35 sacks through its first 10 contests, however.

New England hasn't been a great pass-rushing team this season, managing just 21 sacks on the year, and five of those belong to injured outside linebacker Adalius Thomas. The men responsible for pressuring Roethlisbeger will be outside linebackers Mike Vrabel (39 tackles, 3 sacks) and Pierre Woods (31 tackles, 1 sack), with ends Richard Seymour (43 tackles, 7 sacks) and Ty Warren (38 tackles, 2 sacks) also looking to find their way to the backfield. Seymour and Vrabel both had sacks of Miami's Chad Pennington last Sunday. Ellis Hobbs (34 tackles, 2 INT, 1 sack) and Deltha O'Neal (25 tackles, 3 INT) figure to be matched on Ward and Holmes, with safeties James Sanders (48 tackles, 1 INT) and Brandon Meriweather (51 tackles, 4 INT) helping out as well. New England is allowing opponents to complete 64.4 percent of their passes, which ranks just 26th in the league, and is 18th against the pass overall (215.8 yards per game). The Patriots rank a solid 13th against the run as Week 13 begins (100.2 yards per game), and come off a week in which they held the Dolphins to just 62 yards on the ground. Nose tackle Vince Wilfork (45 tackles, 1 sack) and inside linebackers Tedy Bruschi (62 tackles) and Jerod Mayo (89 tackles) have primary responsibility in slowing the un. Wilfork was credited with four tackles in Miami last week.

WHEN THE PATRIOTS HAVE THE BALL

Cassel's passing exploits of the past two weeks have also spelled big things for his main targets. Among the wide receivers, Wes Welker (80 receptions, 1 TD) and Jabar Gaffney (28 receptions, 2 TD) have both been extremely productive, with Welker coming into Sunday with three consecutive 100-yard games under his belt, and Gaffney having gone for 80+ in his two most recent contests. Randy Moss (54 receptions, 8 TD), who had been quiet apart from a late game-tying touchdown against the Jets, made up for that with a huge eight-catch, 125-yard, three-touchdown day in Miami last Sunday. Tight end Ben Watson (20 receptions, 1 TD) has also developed as a frequent over-the-middle target for Cassel (2615 passing yards, 13 TD, 8 INT). The New England running game has obviously taken a back seat given the pass-heavy approach of the past two weeks, but veteran Kevin Faulk (372 rushing yards, 36 receptions, 4 TD) has remained a major component of the attack. Faulk totaled 105 yards (53 rushing, 52 receiving) and a touchdown on 14 total touches last week. Rookie BenJarvus Green-Ellis (272 rushing yards, 5 TD) scored a touchdown in the win, giving him a score in five of six appearances this year. The o-line seeking to keep Cassel out of harm's way on Sunday has allowed a bloated 35 sacks on the year, including two last week.

There isn't much more to say about the Steelers defense than that it has fewer flaws than any other unit in the league. The pass rush, led by outside linebackers LaMarr Woodley (43 tackles, 10.5 sacks, 1 INT) and James Harrison (70 tackles, 12 sacks, 1 INT), has terrorized opposing quarterbacks and has helped cover up whatever weaknesses and injury problems the club has experienced in the secondary. Ike Taylor (48 tackles) and William Gay (27 tackles) could be the cornerbacks matched with Moss and Welker on Sunday, and safeties Troy Polamalu (49 tackles, 5 INT) and Ryan Clark (56 tackles) will have to lend support over the top. Within the stifling front seven, end Brett Keisel (knee) will not play against the Patriots but all of the other principles will be available. Inside linebackers James Farrior (81 tackles, 2 sacks) and Larry Foote (40 tackles, 1.5 sacks), along with nose tackle Casey Hampton (13 tackles) and end Aaron Smith (36 tackles, 4 sacks), will be the players seeking to control the New England run game. The Steelers held the Bengals to 43 ground yards on 20 carries last time out.

FANTASY FOCUS

Apart from the playmaking defense, there isn't a member of the Steelers that can be considered a can't-miss fantasy option, though certainly Roethlisberger, Parker or Moore, top receivers Ward and Holmes, and tight end Miller have scoring potential. Whoever opens at running back figures to get enough touches to make them worth starting, and of the others, Roethlisberger and Ward are the most consistent numbers-producers. Kicker Jeff Reed doesn't get a ton of chances, but generally makes good on those he does.

Those who have failed to start Cassel the past two weeks have been kicking themselves, and though another 400-yard day is a long shot, he should be able to put up some passing yards on the still-suspect Steelers coverage group. Moss and Welker figure to benefit most when Cassel puts in the air, and Gaffney and Faulk are decent flex plays. The Patriots defense and kicker Stephen Gostkowski are solid options this week as well.

OVERALL ANALYSIS

Given the way the offense has performed of late, it is now more possible than ever to buy the Patriots as a potential playoff team. Cassel and his receivers are beginning to show some real chemistry, and that is bound to serve the team well over the crucial final month. That said, the Steelers defense figures to control this one. Pittsburgh has been dominant in all phases on that side of the ball, and will put enough pressure on Cassel to make his relative inexperience shine through. The Steelers won't run away and hide in this one because their offense isn't good enough to do so, but the defense will make enough big plays to score a road victory.

Sports Network Predicted Outcome: Steelers 20, Patriots 16