Lions' historic collapse: Here's how Detroit let a 17-point lead slip away in NFC Championship loss to 49ers

The San Francisco 49ers are headed back to the Super Bowl, as they defeated the Detroit Lions, 34-31. Trailing 24-7 at halftime, Brock Purdy and Co. engineered an incredible comeback to escape the championship round. The 17-point deficit San Francisco overcame tied the third-largest comeback in a conference championship game, and was the largest halftime deficit overcome in a conference championship game.

The Lions dominated the first half of action, but everything seemingly went wrong in the final two quarters. How did this happen? Let's take a look.

Turnover on downs on the first possession of the second half

The 49ers got the ball to start the second half, and they went 50 yards on nine plays, while Jake Moody hit a 43-yard field goal to trim the deficit to 14 points. The Lions offense then went all the way from its own 25-yard line to the 49ers' 28-yard line. In field goal range, Dan Campbell was faced with a fourth-and-2. He elected to go for it, but Jared Goff could not connect with Josh Reynolds. That provided momentum for the 49ers.

An amazing catch and a missed opportunity

On the 49ers' next possession, Purdy relied on star wideout Brandon Aiyuk to move the chains. An overthrow turned into a huge pickup of 51 yards, as the ball bounced off Kindle Vildor's facemask, and into the hands of Aiyuk.

This probably should have been an interception, but Aiyuk took advantage of the defensive back's miscue. 

Three plays later, Aiyuk finished the drive with a touchdown, trimming the deficit to just seven points with a little over five minutes remaining in the third quarter. 

Jahmyr Gibbs' fumble

In the blink of an eye, we had ourselves a game. And in another blink of an eye, the 49ers had the ball again.

On the Lions' first play from scrimmage following the Aiyuk touchdown, Gibbs coughed up the rock, and San Francisco recovered at Detroit's 24-yard line. 

Four plays later, Christian McCaffrey's second rushing touchdown tied the game at 24 apiece. 

A drop on third down

The Lions offense had to get back on track, but instead, it went three-and-out. Reynolds appeared to have a third-down conversion, but dropped the pass. 

To make matters worse, the Lions couldn't down a perfectly placed punt at the 1-yard line, which resulted in a touchback. The 49ers then went 65 yards on 11 plays, and Moody hit a 33-yard field goal for their first lead of the game. 

A potential TD drop and another turnover on downs

Now down three points early in the fourth quarter, the Lions offense again took the field. After Jameson Williams made an impressive 22-yard grab which almost was intercepted off the bobble, he dropped what could have been a touchdown deep down the right sideline on a first-and-10.

Three plays later, the Lions were faced with a fourth-and-3 from the 49ers' 30-yard line. Instead of attempting the field goal and potentially tying the game, Campbell again elected to go for it, but Goff could not hook up with Amon-Ra St. Brown. 

What followed was a seven-play, 70-yard drive from the 49ers, which was capped by an Elijah Mitchell touchdown to extend San Francisco's lead to 10 points.

A (poorly executed) TD drive

By this point, the Lions had been outscored 27-0 in the second half. With three minutes remaining in the game, Detroit had to work fast. Goff did lead a 75-yard touchdown drive to pull within three points, but it was not a perfect possession.

On a first-and-goal with 1:16 remaining, Anthony Firkser did not score on a play where he probably should have, instead stepping out at the 1-yard line. 

On third-and-goal, the Lions ran the ball with David Montgomery, who was stuffed for a loss of 2 yards. Here, Detroit was forced to spend its first timeout with one minute remaining. Goff did hit Williams for a 3-yard touchdown on fourth-and-goal, but the onside kick that came next was unsuccessful. 

The 49ers took over at the Lions' 44-yard line, and since Detroit had just two timeouts remaining, that was game. 

The Lions defense fell apart

Let's take a step back and examine what happened in the second half at large. The Lions defense, which held San Francisco to just seven points in the first half, completely fell apart. Just look at the 49ers' second-half drives, not counting the final kneeldowns. 

Questionable play calls, turnovers, dropped passes and poor defense led to the 27-7 run Detroit was on the wrong end of. The Lions had an incredible season overall, and reaching the NFC Championship was an impressive feat. This franchise is very much on the right track, but how the 2023 campaign ended will sting all offseason.