We're eight weeks into the NFL season and only two undefeated teams remain: The New England Patriots (8-0), who won the Super Bowl last year, and the San Francisco 49ers (7-0), who finished 4-12.

The road to 16-0: The Patriots are favored to win all of their remaining games with the biggest test coming on Sunday night in Baltimore (57% win probability), while the 49ers are favored to win 7 of 9.

Patriots in a nutshell: When the Pats went 16-0 in 2007, the offense rewrote the record books. This time around, it's the defense leading the way.

By the numbers: New England's veteran-laden defense has scored more TDs (6) than it has allowed (4) and leads the NFL in virtually every category, including sacks (31) and interceptions (19). For reference, no other team has more than 10 picks.

New England's veteran-laden defense has scored more TDs (6) than it has allowed (4) and leads the NFL in virtually every category, including sacks (31) and interceptions (19). For reference, no other team has more than 10 picks. Yes, but: Four of their wins came against the NFL's three worst offenses (Dolphins, Redskins, Jets twice) and their other four came against the 28th-ranked offense in terms of yards (Steelers), the 24th-ranked offense (Giants), the 20th-ranked offense (Browns) and the 19th-ranked offense (Bills).

Four of their wins came against the NFL's three worst offenses (Dolphins, Redskins, Jets twice) and their other four came against the 28th-ranked offense in terms of yards (Steelers), the 24th-ranked offense (Giants), the 20th-ranked offense (Browns) and the 19th-ranked offense (Bills). The bottom line: While the Patriots' cupcake schedule shouldn't take away from their impeccable start, any "they haven't played anybody!" gripes are legitimate because, well, they haven't. That'll change in November, though.

49ers in a nutshell: Kyle Shanahan has emerged as this year's Sean McVay — a football guru with a gift for designing plays. Meanwhile, the defense has been lights out and clearly the second-best unit in the league behind New England.

Offense: The Niners rely heavily on play-action (34.1% of dropbacks), and Shanahan is a master of misdirection. When Jimmy Garoppolo hands the ball off, there's almost always some kind of motion to confuse the defense (prime example).

The Niners rely heavily on play-action (34.1% of dropbacks), and Shanahan is a master of misdirection. When Jimmy Garoppolo hands the ball off, there's almost always some kind of motion to confuse the defense (prime example). Defense: The defensive front, led by No. 2 pick Nick Bosa and $85 million free agent addition Dee Ford, has been flat-out dominant. And the secondary — which, like the offense, uses lots of misdirection (i.e. disguised coverages) — has surprised everybody.

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