PITTSBURGH (AP) – Ben Roethlisberger has known nothing but success since becoming the Pittsburgh Steelers’ starting quarterback five weeks ago. He also knows this is the week he is supposed to learn about failure.

These won’t be the Bengals or the Browns he’s facing – he has yet to play against a winning team – but the defending Super Bowl champion New England Patriots. Winners of 21 in a row and a record 18 straight during the regular season, they’re not just the best team he’s faced, they’re the best of the best.

Roethlisberger has heard he’s in over his head, that a quarterback with so little experience can’t possibly be ready for all the Patriots will throw at him – the disguised blitzes, the trick coverages, the mistake-free execution of a complicated defensive game plan.

Just watching the Patriots (6-0) play on videotape is impressive enough to Roethlisberger, who is 4-0 as an NFL starter.

“In watching a few games of theirs, I’ve seen more things than I’ve ever seen in my life on defense,” Roethlisberger said Wednesday. “There will be times when they’re showing nobody and they bring the house (on a blitz). There will be times when they’re showing everybody and will bring nobody. It will be a challenge.”

Still, nobody in his locker room seems overly nervous that the Steelers (5-1) are going into their biggest game since their January 2003 playoff loss to Tennessee with the NFL’s most inexperienced starting quarterback.

Maybe it’s because of the uncommon poise and confidence he displayed while leading fourth-quarter comeback victories against the Cowboys and Bengals, but the Steelers don’t think Roethlisberger vs. the Patriots is a mismatch.

“He is very mature for his age (22),” coach Bill Cowher said. “While certainly he is going to have a better feel for this offense as he continues to grow in it, he has done a very good job of handling everything that has come with it. He has not been overwhelmed by anything.”

That contrasts to former Steelers quarterback Kordell Stewart, who looked confused and frustrated during losses to New England in the January 2002 AFC championship game and the 2002 season opener.

“Ben will handle it,” wide receiver Hines Ward said. “Dallas tried to bring pressure, but he eluded the pressure and got outside the pocket. I’m pretty sure (Patriots coach Bill) Belichick’s going to have something, he’s going to try to take away your strengths … so we’ll see.”

While Roethlisberger’s inexperience may be a significant disadvantage the Patriots can exploit, some New England players suggested it can be difficult to prepare for a quarterback who has played so little.

“The times we’ve seen him a little confused, he’s gotten out of the pocket or gotten away from the blitzes, and he has thrown the ball downfield and made plays,” linebacker Willie McGinest said. “I met the kid in the offseason, and he has that (presence). He’s not going to get shattered too easily. You’re not going to really mess him up mentally.”

Roethlisberger’s size – 6-foot-5, 240 pounds – might have something to do with that. He has the strength to stand up to pass rushers, yet is more mobile than Tommy Maddox, who started Pittsburgh’s first two games before injuring a right elbow tendon.

Since then, Roethlisberger has completed 78 of 113 passes for 937 yards, seven touchdowns and four interceptions, with two interceptions coming while he threw on nearly every down in the second half of a 30-13 loss at Baltimore on Sept. 19.

“His physical strength and size have helped him more than people might have thought it would because you just can’t get him down,” Belichick said. “He just stands in there, waits until somebody gets open and just throws it.”