As NFL matchups go, this one is a classic: unstoppable offense against impenetrable defense.

The second round of the playoffs begins Saturday in San Francisco, where one of the league’s top defenses — the 49ers yielded 229 points and ranked fourth overall in yards allowed, first against the run — takes on Drew Brees and the Saints’ record-setting attack.

If defense wins championships, as has been the theory in pro football for decades, the edge clearly belongs to the 49ers. Then again, the NFL hasn’t seen an offense as prolific as the Saints.

“They’ve been very consistent all year,” Saints coach Sean Payton said of the NFC West champion Niners (13-3). “The formula has been outstanding defense. … They’re the No. 1 team in taking the football away and they’re the No. 1 team in protecting the football offensively. Those are significant numbers.

“I think you can see week to week on tape their production on both sides of the ball. You’re talking about a Pro Bowl punter and a kicking game that’s near the top of the league in almost every statistic. In all three phases, they’ve been consistent. They’ve received great production and as a result they’ve played very well.”

The 49ers have five All-Pros: linebackers Patrick Willis and NaVorro Bowman, defensive tackle Justin Smith, who also plays a lot at end, kicker David Akers and punter Andy Lee. Their offense has been so efficient that San Francisco had only 10 giveaways, which equaled the 2010 Patriots for fewest in NFL history.

“It’s going to be a battle,” Willis said. “We know that and I’m sure they know that as well. They’re going to do what they need to do to prepare to come in to play against us and we’re going to do that same (thing). We’ll see where the chips lay when the game is over, but we’re certainly going to come with everything we have. It’s either win or go home.”

The Saints tore through the NFL, setting NFL marks for total yards on offense (7,474) and yards passing (5,347, including sacks), with Brees shattering Dan Marino’s 27-year-old record of 5,084 yards passing by throwing for 5,476. He had 468 completions, breaking Peyton Manning’s 2010 mark of 450, and completed 71.6 percent of his passes, breaking his own 2009 record of a 70.6 completion percentage.

Darren Sproles had an NFL-record 2,696 combined yards, easily breaking the previous mark of 2,690 set by Derrick Mason with Tennessee in 2000.

“We always go into every game with an aggressive mentality,” Brees said. “We’re going to be balanced, but within the framework of that we’re going to take our shots. We’re going to throw the kitchen sink at everybody with our tempo, personnel groups, formations, running the ball, outside, drop-back pass, bootlegs, heavy play-action, everything. But within the framework of that, you understand, especially early on, you check it down, move on.”

Also looking to move on Saturday are the AFC East champion Patriots (13-3), who host the AFC West winners, the Denver Broncos (9-8). On Sunday, AFC South winner Houston (11-6) is at AFC North champ Baltimore (12-4) before defending Super Bowl champion Green Bay (15-1) hosts NFC East champ New York (10-7).

New England has lost its last three postseason games: the 2008 Super Bowl to the Giants, then home matchups with Baltimore and the Jets the last two Januarys. Now comes the Tim Tebow phenomenon, and it’s become difficult to doubt Denver with the way it has responded to tough times.

After blowing a 14-point lead and being forced to overtime by Pittsburgh, the Broncos needed all of one play — a dynamic 80-yard catch-and run by Demaryius Thomas — to beat the far more experienced Steelers.

The challenge is just as formidable in Foxborough.

“You’re definitely at a high, you’re feeling great, a lot of momentum, and that’s good,” Tebow said. “But you really have to take that enthusiasm, that momentum into the next week’s work, using that as fuel for next week and trying to continually improve on that. I think you can’t necessarily relish on it too much because the next day we have to get ready for a big game and the Patriots.”

Baltimore is getting ready for its first playoff home game under coach John Harbaugh, Jim’s brother. The Ravens have made the playoffs in all four seasons under Harbaugh, but as wild cards.

They won their eight home games in 2011, including beating the Texans 29-14 in October.

“We did what we had to do to get that first-week bye,” defensive end Cory Redding said. “We came out of the back stretch 3-1, and that was our main focus. Guys are fighting on the field with big gashes down their legs and almost bruised ribs, messed up knees and toes and ankles and hands, and yet we still fought our way.

“That was the biggest thing. We got that accomplished. We got control in the AFC North accomplished, and now it’s time to rest, recover and get ready for the second season and winning Game 1. That was the mindset for the guys. It was a big accomplishment.”

Like the Texans, the Giants are trying to accomplish a difficult feat: winning at Lambeau Field, where the Packers were 8-0, and defeating a team that beat them in early December in the Meadowlands.

New York is banking on a revived defense, especially the pass rush, and an invigorated running game.

“Persistence … and the ability to ride the ups and the downs and stay together,” Giants coach Tom Coughlin credited for his team’s recent surge. “The development of the feeling of ‘team.’ The confidence that grows from a little bit of success. The ability to put some of the pieces to the puzzle together that haven’t been there, that weren’t there, that do breed the confidence.”

ATLANTA (AP) — Those cute mail-order chicks that wind up in children’s Easter baskets and backyard farms have been linked to more than 300 cases of salmonella in the U.S. — mostly in youngsters — since 2004.

An estimated 50 million live poultry are sold through the mail each year in the United States in a business that has been booming because of the growing popularity of backyard chicken farming as a hobby among people who like the idea of raising their own food.

But health officials are warning of a bacterial threat on the birds’ feet, feathers, beaks and eggs.

NEW YORK (AP) — Leo Dillon, the groundbreaking illustrator who collaborated with his wife, Diane, on dozens of books for kids and adults and became the first African-American to win the Caldecott Medal for children’s books, has died. He was 79.

Dillon died May 26 at Long Island College Hospital from complications after lung surgery, publisher Scholastic Inc. announced Wednesday. Harlan Ellison, a close friend, wrote on his website that “Half my soul for 50 years went with him.”

WASHINGTON (AP) — The Obama administration is moving to impose stiff new tariffs on wind-energy towers made in China, the latest strike in an escalating trade war over clean energy.

The Commerce Department said in a preliminary decision Wednesday that Chinese companies have received government subsidies on steel wind towers ranging from about 14 percent to 26 percent. The decision could result in tariffs of those amounts being imposed on about a dozen Chinese companies that export large numbers of steel wind towers to the United States.

It follows a Commerce Department decision this month to impose tariffs averaging about 31 percent on solar cells and panels imported from China.

China has called the U.S. action on solar equipment unfair and warned that higher tariffs could hurt efforts to promote clean energy.

WASHINGTON — The Obama administration added new sanctions on a Syrian bank Wednesday as a top White House official said the U.S. wants to economically throttle the regime of Syrian President Bashar Assad and cut off salaries of pro-government thugs blamed for the grisly massacre in Houla.

The Treasury Department said the Syria International Islamic Bank has been acting as a front for other Syrian financial institutions seeking to circumvent sanctions. The new penalties will prohibit the SIIB from engaging in financial transactions in the U.S. and will freeze any assets under U.S. jurisdiction.

BILLINGS, Mont. (AP) — The U.S. Army Corps of Engineers says the price tag on proposed fixes to Montana’s Fort Peck Dam following major flooding along the Missouri River could top $225 million.

But with money short, Corps officials said Wednesday they will be able to afford only $46 million in interim fixes for now.

Record snowfalls and massive spring rains in Wyoming and Montana last year prompted the release of unprecedented volumes of water from the Corps’ six Missouri River dams.

The torrent damaged Fort Peck’s spillway gates and eroded areas downstream from the dam, located at the top of the Missouri River system.

Fort Peck Project Manager John Daggett says the planned repairs will ensure the spillway can be used to safely release water during future flooding.