The New England Patriots' pursuit of perfection has nearly been derailed twice in the last two weeks. The Pittsburgh Steelers think they might be the team to finish the job.

New England looks to become the fourth team in the modern era to start an NFL season 13-0 -- and the first to win 16 straight regular-season games since the Steelers in 2004-05 -- when it hosts Pittsburgh on Sunday.

If there was a team equipped to end the Patriots' streaks, the Steelers (9-3) may fit the bill. After all, Pittsburgh ended New England's league-record 21-game winning streak -- 18 in the regular season -- on Oct. 31, 2004, when it was in the midst of winning 16 in a row. The Patriots returned the favor on Sept. 25, 2005, stopping the Steelers' streak with a come-from-behind win at Heinz Field.

Even though the Steelers are heavy underdogs this time heading into Foxborough, their top-ranked defense has allowed the fewest points, total yards and passing yards in the NFL. New England is No. 1 offensively in each of those categories.

"The New England Patriots are a very good football team, to say the least," Steelers coach Mike Tomlin said. "(But) this isn't Appalachian State against Michigan."

Then again, that game worked out fairly well for the longshot.

The only teams to begin a season 13-0 since the 1970 AFL-NFL merger were Miami (1972), Denver (1998) and Indianapolis (2005).

The Patriots were rarely tested in their first 10 contests, winning by an average of 25.4 points. A fourth-quarter deficit at then-unbeaten Indianapolis on Nov. 4 was their only real anxious moment in the first two months. After rallying from down 10 to beat the Colts 24-20, New England manhandled Buffalo 56-10 in its next game and was favored to beat Philadelphia by an NFL-record 24 1/2 points at home on Nov. 25.

But the Eagles led 28-24 midway through the fourth before Laurence Maroney's touchdown run gave the Patriots a lead they would not relinquish.

If that wasn't enough of a scare, New England got another one Monday night at Baltimore. Facing a Ravens team that hadn't found much of an offensive pulse this season, Willis McGahee ran for 138 yards and the Patriots were trailing 24-20 when they got the ball with 3 1/2 minutes to play.

Like he had done 26 previous times when tied or trailing in the fourth quarter, Tom Brady delivered a game-winning drive. He took New England 73 yards in the final minutes, converting on two fourth downs, and found Jabar Gaffney for the winning touchdown with 44 seconds left.

"We made enough plays at the end," said Brady, whose 257 yards passing was his third-lowest total of the season. "A lot of room to improve in the final four weeks. There's things we could've certainly done better ... we kept clawing back."

New England can clinch a first-round bye with a win, and will lock up home-field advantage throughout the AFC playoffs with a win and a Colts loss to Baltimore.

Though he didn't put up his typically eye-popping statistics against the Ravens, Brady is still on pace to break Peyton Manning's single-season touchdown record of 49, and has a shot to break Dan Marino's record of 5,084 yards.

Brady's career season has coincided with the re-emergence of Randy Moss as one of the league's premier receivers. He has 75 receptions for 1,129 yards and already has tied his career high with 17 touchdown catches, five more than the previous club record.

The Patriots are on pace to be the highest-scoring team since the AFL-NFL merger, averaging 39.1 points. The record is held by the 1998 Minnesota Vikings, who averaged 34.8 points, largely because of the production of a rookie named Moss.

"Some defenses might be, 'Oh my gosh, I'm going against Randy Moss, Wes Welker, Donte Stallworth. Tom Brady is the quarterback.' Some people might get enamored with that," Steelers offensive lineman Max Starks said. "But I definitely don't see that in our defense."

New England's problem the last two weeks has been its defense. Though the Patriots are third in the NFL in total defense, giving up 289.4 yards per game, they allowed an average of 383.5 yards against Philadelphia and Baltimore.

"I felt (the Baltimore game) was the first time all year that we got bullied," Patriots safety Rodney Harrison said. "(That) game showed we have a lot of problems and we're going to look at film and make corrections before we play Pittsburgh."

The Steelers are looking for their third win in a row, though neither of the last two victories were particularly inspiring. They yielded just 204.0 yards on average to Miami and Cincinnati, but sloppy field conditions limited the Pittsburgh offense in a 3-0 win over the Dolphins and four turnovers held the Steelers back last Sunday night in a 24-10 victory over the Bengals.

"We weren't perfect, but the guys were resilient and found ways to win the game," Tomlin said. "It is pretty uncommon, I guess, when you lose a turnover battle the way we did in that football game (4-1) and still get a victory. It speaks to the mettle of our defense."

Pittsburgh quarterback Ben Roethlisberger hasn't been as masterful as Brady, but he's been the next-best thing in the AFC. His 25 touchdown passes and 8.0 yards per attempt rank second to the Patriots' signal-caller, and his 102.9 quarterback rating is third.

But after posting passer ratings of at least 99.9 in six of the team's first eight games, Roethlisberger hasn't been above 81.3 in the past three weeks, throwing for less than 200 yards in each game with three touchdowns and four interceptions.

As Roethlisberger has struggled, so has running back Willie Parker. Though he's the AFC's leading rusher with 1,093 yards, the speedy Parker has been held under 100 yards the past three weeks, averaging just 3.0 yards per carry, and has scored only twice all season. He lost two fumbles last week and could have had another two if the Steelers didn't win replay challenges on both.

Pittsburgh's chances would be boosted if it can get some players back on the field, but wide receiver Santonio Holmes (ankle) and safety Troy Polamalu (knee) continue to struggle with injuries.

Polamalu will likely miss his third straight game after sitting out practice for the second day in a row Friday, while Holmes struggled through the team's workout. Holmes has also missed the last two games.

The Steelers can win the AFC North with a win over New England coupled with a Cleveland loss, while they can secure at least a playoff spot with a win and a Tennessee loss.

Pittsburgh lost its only visit to Foxborough -- in 2002 -- since winning there on Dec. 13, 1997.