Super Bowl 58: The 49ers' linebacker duo of Fred Warner and Dre Greenlaw is the NFL's best, but they'll face a tough test against the Chiefs

• Two of the best: Among the 63 linebackers who have played at least 1,500 snaps — including the postseason — over the last three seasons, Dre Greenlaw's 80.1 PFF grade ranks ninth, while Fred Warner's 91.0 leads the pack.

• The toughest test yet: Patrick Mahomes boasts the third-highest PFF grade in the NFL this season when targeting linebackers (93.2), while his 110.5 passer rating on these throws also ranked third in the NFL.

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The San Francisco 49ers‘ linebacker duo is widely regarded as the best in the NFL. But what makes Fred Warner and Dre Greenlaw so good, and are they really the league's best tandem?

Among the 63 linebackers who have played at least 1,500 snaps — including the postseason — over the last three seasons, Greenlaw's 80.1 PFF grade ranks ninth, while Warner's 91.0 leads the pack. They are the only players in the top 10 to have played together for a significant amount of time.

However, their play in coverage might be even more impressive than their overall grade and might be more relevant for Super Bowl 58, as well.

Warner again leads the NFL in this category over the last three seasons with a coverage grade of 91.0, whereas Greenlaw's 87.4 ranks fourth. Quarterbacks targeting San Francisco linebackers — including other 49ers players at the position — this season posted a completion percentage of 74.8%, which was the fifth-lowest in the NFL. Those linebackers allowed a passer rating of just 91.4 when targeted, tied for the sixth-lowest in the league. They also surrendered a first down on just 28.4% of targets, the fifth-lowest rate.

It is not just that Warner and Greenlaw stand out in coverage. It is that they do so while getting tougher assignments than most other linebackers. Their coverage ability allows defensive coordinator Steve Wilks — and previous defensive coordinator DeMeco Ryans — to play more zone coverage and better disguise coverages.

Even though it would be a nearly impossible assignment for most linebackers, Ryans and Wilks were not afraid to ask Warner and Greenlaw to run 20-plus yards downfield with the likes of CeeDee Lamb, Marquise Brown and Christian Kirk — and all of those situations have taken place over the last 13 months.

Over the last two seasons — including the postseason — Warner has been targeted 14 times on passes that traveled at least 20 yards in the air, the most among linebackers, while Greenlaw is tied for third with nine such targets.

They are not only asked to cover these wide receivers down the middle of the field, but they are also not a liability for the defense in these situations.

Greenlaw allowed four receptions on his nine targets, and he also recorded an interception and broke up a pass.

Warner has done even better on the deep passes going his way. Although he allowed five receptions — including a touchdown — on his 14 targets, he has also recorded four interceptions and forced three incompletions, including one that turned into an interception for a teammate. As a result, he has allowed a passer rating of just 68.2 on deep passes, which ranks seventh among linebackers who have been targeted on at least five deep passes over the last two seasons.

San Francisco’s star tandem will be put to the test on Sunday, and they will need to be at their best, given that they are facing Kansas City quarterback Patrick Mahomes. The Chiefs signal caller had the third-highest PFF grade in the NFL this season when targeting linebackers (93.2), while his 110.5 passer rating on these throws also ranked third in the NFL.

If any linebacker duo in the NFL can make it really hard on Mahomes in the middle of the field, it’s Warner and Greenlaw.