The 49ers and Saints might be the two best teams in the NFC. New Orleans took over the No. 1 seed in the NFC after the 49ers’ loss last week and subsequent Seattle win Monday night.

Both clubs have very good defenses to complement diverse offenses capable of racking up 30 points. With tiebreakers looming to decide first-round byes and home field advantage, this is a crucial game in the NFC playoff picture. It’s not necessarily a must-win for the 49ers, but it’s as close as a game can get without being one.

Here are the three key matchups that’ll decide Sunday’s game:

Nick Bosa vs. Saints tackles

Whether its Terron Armstead, Ryan Ramczyk or Patrick Omameh, Bosa will need to win his matchups on the edge. Armstead is questionable with an ankle injury, in which case Omameh would get the start at left tackle. That’s the matchup we’ll likely see most with Bosa, and the on that’s most crucial Sunday. The 49ers’ pass rush is the NFL’s best when the rookie defensive end is getting loose and collapsing the pocket from the quarterback’s blind side. Their run defense will also need to effectively set the edges, which also starts outside with Bosa. If he’s stymied and ineffective, it’ll be a long day for the 49ers defense.

Michael Thomas vs. 49ers secondary

Thomas’ versatility means we’ll likely see him against all of the 49ers corners at some point. Asking that unit to shut Thomas down is probably unrealistic. He’s on pace to break the NFL single-season receptions record, and his worst game of the year in terms of catches came against Seattle when he posted five receptions for 54 yards and a touchdown. He’s arguably the best receiver in the NFL going against the NFL’s stingiest pass defense. San Francisco hasn’t allowed a 100-yard receiver since Week 1, and most of the big performances against them were aided by one long reception. If the 49ers can keep Thomas from having a massive game, they have a chance of keeping the Saints offense from putting a big number on the scoreboard.

Jimmy Garoppolo vs. turnovers

The two 49ers losses have one thing in common from the offense’s perspective. Garoppolo turnovers leading to points in games decided by a field goal. Seattle had an interception and two fumble recoveries against Garoppolo. Baltimore had a fumble recovery. All four of those led to touchdowns. Sunday will likely be another closely-contested game, which means Garoppolo has to be extra cautious with the football. The Saints have a very good pass rush that’ll pin its ears back and wreck a game if San Francisco has to play from behind, so taking care of the ball, especially early in the game to allow the 49ers to get in front and play from ahead will be of the utmost importance.