San Francisco 49ers need to fix their mistakes. Fast.

The San Francisco 49ers got away with one. They know it, too.

The NFC’s No. 1 seed sure didn’t play like one Saturday night, winning as much because of the Green Bay Packers’ gaffes as anything they did. Yes, they’re moving on, but they’re going to have to clean things up on offense, defense, special teams and coaching if they want to make it to the Super Bowl.

"That game felt off pretty much the whole game until the end there," said Christian McCaffrey, who ran for two touchdowns in the second half, including one with 67 seconds left to give the 49ers the lead for good.

"To be able to persevere through the adversity, to have mature guys on the team who can strap up and go out there and find a way to get a win, it’s a sign of a good team. Even when you’re playing bad."

The whole point at this time of year is surviving and advancing. By that measure, San Francisco is fine. They’re one of just four teams still playing, and they’ll host the Detroit Lions in the NFC Championship on Sunday.

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But the juggernaut of the regular season, San Francisco was not against the Packers.

Maybe it was the rain, which Brock Purdy acknowledged affected the accuracy on some of his throws. Though Jordan Love played in the same conditions and, horrendous throw to end the game aside, didn’t seem to have the same issues.

Maybe it was the rust. The 49ers clinched the No. 1 seed on Jan. 1, allowing them to rest most of their top players for the regular-season finale. Add in the first-round bye, and that’s three weeks since McCaffrey, Purdy, George Kittle, Dre Greenlaw, Arik Armstead and several other key 49ers had seen game action.

Maybe it was the shoulder injury that knocked Deebo Samuel out of the game in the second quarter. The 49ers are a lesser version of themselves without their electric and elusive playmaker, as we saw during the regular season. Samuel suffered a hairline fracture in his shoulder against the Cleveland Browns, then missed the 49ers’ next two games.

The Niners lost all three.

The reasons for San Francisco’s malaise really don’t matter, though. At this point in the year, the 49ers have to be able to adapt to everything. That’s what playoff teams do.

The ones that go far, that is.

"I don’t know what the reasons were," McCaffrey said. "We’ll never know for sure. I don’t like making huge broad statements after games. It’s just little things here and there that I know we can get corrected."

Say this for the 49ers: At least they owned their woes. They didn’t pretend it wasn’t as bad as what everyone saw or get defensive about the mistakes. They know this wasn’t what they’re capable of and they promised to get it fixed before next weekend.

That has to start with Purdy, who was masterful on the final drive but meh until then. He was six of seven on the final drive, but 17 of 32 before that. He finished without an interception, but only because Darnell Savage dropped what likely would have been a pick-six.

That final drive takes away some of the sting − as does the knowledge Purdy and the 49ers have the benefit of multiple players who can blow up a defense at any moment. As they did against Green Bay. On consecutive plays in the third quarter, Kittle had a 32-yard reception and McCaffrey ripped off a 29-yard scoring run.

"Our offense wasn’t as rhythmic as it usually is. Our defense − it probably wasn’t our best game of ball we’ve played all year. But slipping away? No," Kittle said. "It was more of a, `We know the type of team that we have, guys. Go out there and just do what you can do on every single play,’ and I’m very confident in our abilities to go down there and get a win."

The defense was gashed for 108 yards by Aaron Jones, almost half of which (53 yards) came on one play. According to Josh Dubow of The Associated Press, Jordan Love was 15 for 22 for 168 yards, two TDs and no interceptions on the Packers’ first six possessions.

On the last four, however, the 49ers’ defense made his life downright miserable. He was six of 12 for 30 yards and two interceptions, including one that ended Green Bay’s final drive.

"It’s all learning. The offense and the defense made a lot of mistakes that we need to clean up if we want to win," Nick Bosa said.

The 49ers did win. This time. But you can only get away with so many games like this, and the 49ers might not be so fortunate next time around.

Follow USA TODAY Sports columnist Nancy Armour on social media @nrarmour.