The New England Patriots take on the Denver Broncos in the NFL’s marquee matchup Sunday.

Of course, it provides the game’s best quarterback rivalry, with New England’s Tom Brady facing Denver’s Peyton Manning for the 16th time. Brady holds a 10-5 edge, but Manning has won the last two big games, the AFC championship games after the 2006 and 2013 seasons.

But in this particular game on this particular Sunday, all eyes should be on the secondaries. That’s where the two NFL powers made their boldest offseason moves.

The Broncos, seeking help because of the departure of long-time cornerback Champ Bailey, signed Aqib Talib in March to a six-year contract worth $57 million. Talib, of course, is a former Patriot and was, without question, their best cover back in the 19 games he played for them.

In fact, it wouldn’t be an overstatement to say that Talib was likely the most irreplaceable Patriot other than Brady during his tenure at Gillette Stadium. His injuries in the last two AFC championship games were critical factors in New England losses. Last year he was hurt with 13:31 left in the half on a Wes Welker pick. Denver led 3-0 at the time; Talib never returned, and Denver won 26-16.

To offset his loss – and the Patriots tried hard to bring him back, Talib telling the Boston Herald this week that he “definitely came close” to returning – the Patriots first signed cornerback Brandon Browner (formerly of Seattle). Two days later, New England added Darrelle Revis, long considered the best cornerback in the game but still recovering from a knee injury that kept him out of all but two games in the 2012 season.

Browner, at 6-foot-4, 221 pounds, and Revis, at 5-11, 198, have the size and ability to shut down the game’s best receivers. And the anticipation of playing the Broncos again is a big reason why Coach Bill Belichick wanted them in New England.

If the Patriots are going to get to the Super Bowl again, they’re going to have to get past Denver. And if they’re going to get past Denver, they need to contain the Broncos’ passing game.

They couldn’t do it in the AFC championship game in January, when Manning threw for 400 yards and two touchdowns.

Now, with Revis and Browner coming around, the Patriots at least have a chance to slow the Broncos. New England has the second-best pass defense in the NFL, allowing just 210.9 yards per game, and the secondary will need to be at its best against Denver.

The Broncos come in with a 6-1 record and are averaging an NFL-best 32 points. The Patriots are 6-2 and averaging 29.8 points, third-best in the league.

Revis has been as advertised. He leads the Patriots in interceptions (two) and passes defended (six). Browner missed the first six games (four because of a suspension, two because he was hurt) but has made a big impact in the two games he’s started.

They will both need to be at their best Sunday because the Broncos have four of the NFL’s best receivers.

Wide receivers Demaryius Thomas and Emmanuel Sanders have each caught 47 passes, with Thomas scoring six touchdowns and Sanders four. Tight end Julius Thomas has caught 30 passes with nine touchdowns. And a former Patriot, Wes Welker, is settling back into his role as the best slot receiver in the NFL after sitting out a suspension.

But beyond their obvious talent, the Broncos’ receivers provide a physical challenge. Demaryius Thomas is 6-foot-3, 229 pounds; Julius Thomas is 6-5, 250. There are not many cornerbacks who can match up with them physically. Revis and Browner are among the few.

Manning, speaking early last week, said their presence changes what the Patriots can do defensively.

“With the excellent cover corners, it allows them to do a lot of things and … put those guys out there because they have such great cover skills,” he said.

Manning said Revis in particular can disrupt an offense.

“If you’re throwing against him, you better be accurate and you better be running really good routes,” said Manning.

The Patriots haven’t said much about how they plan to defend the Broncos’ passing game. Then again, Belichick never reveals strategy, even after a game. But it seems likely that Revis and Browner will be matched up one-on-one with two of the Broncos’ receivers, most likely the Thomases.

Browner will likely draw Julius Thomas. As unusual as it is for a cornerback to cover a tight end, Belichick has chosen that option in the past. Talib shut down New Orleans’ Jimmy Graham last year, holding him without a catch, and last week Browner often lined up on Chicago’s Martellus Bennett.

Whatever the Patriots do, Denver Coach John Fox knows it will be difficult to counter.

“They’re going to be in your face,” he said. “They put their corners on your guys and challenge them. They mix up whether they’re single-high or split safety, and they do a great job disguising it.

“You go out and get a guy like Browner, a very veteran guy; obviously Revis (is) a very, very capable guy.”

As for the Broncos’ defense, Talib possibly could line up against Patriots tight end Rob Gronkowski, who makes New England’s offense go.

The buildup to this game has obviously focused on Brady and Manning. But the cornerbacks deserve a lot of attention, too. Talib has 25 career interceptions, five of which he has returned for touchdowns. Revis has 23 career interceptions, three of which he has returned for scores.

On Sunday they will face their biggest challenges of the season. And come Sunday night, we’ll know who had the better offseason.

Sit back and enjoy. It should be a good one.