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Nick Bosa gets home again to take Jared Goff down for an eight-yard loss, and the Lions are then facing another third and long, this time 18 yards needed.

It's third and 12 yet the Lions run it, as they've been doing all season, and they only go and get the first down thanks to Jahmyr Gibbs yet again.

We're just not used to seeing this 49ers defence just pushed around as much as Detroit are managing to do right now.

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Detroit still keeping with the run game and it keeps working, with David Montgomery pounding the rock and churning out yards - making first downs too.

Detroit reach midfield with just over two minutes on the clock.

Brock Purdy scrambling around in the backfield and throwing a hopeful one up for a diving Brandon Aiyuk, but he just can't gather it in and San Francisco have to punt.

There's still five minutes left in the half, and Detroit will fancy adding to their lead before going back into the locker rooms.

Jason Bell, former NFL cornerback on Sky Sports: "You have to capitalise on any errors and the Detroit Lions have done that.

"They have let you know that if you make any mistakes, they will respond.

"This offense is on fire!"

Brock Purdy almost disappears in a crowd of Detroit defenders and tries to force a through out that trouble, but he only succeeds in floating the ball to Detroit's Malcolm Rodriguez.

Purdy was hampered as he tried to throw that ball but it still wasn't the best decision. Detroit's ball!

Deebo Samuel gets a first down on a jet sweep, has to stutter for a bit then dives through some tackles in the kind of tough run only he can make on this 49ers team.

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Ndamukong Suh, former Super Bowl winner, on Sky Sports: "It was definitely a fast start from Detroit Lions but the 49ers seem to have settled and worked out what Detroit want to do.

"Now, they are finding opportunities to disrupt the Lions, slow them down and get their offence back on the field."

A first stop of the day for the San Francisco defence and Detroit kick it away - Dan Campbell must have been tempted to either run the fake or even go for it on fourth down.

No team in the league has gone for it more on fourth down than the Lions since Campbell took over.

Dre Greenlaw smashes rookie tight end Sam LaPorta but comes off second best with an arm or shoulder injury - maybe a stinger after a bone-crushing collision.

Nick Bosa hasn't had a sack for four games but he gets one in this most crucial of games at a crucial time, wrapping up Jared Goff and forcing third a long.

Ben Collins
BBC Sport

San Francisco coach Kyle Shanahan said during the week that having to come from behind to beat Green Bay last week wasn't such a bad thing. It's not often his team has been put in positions like that, and perhaps it has stood them in good stead.

I mean, being 14-0 down at home after the first quarter of a Conference Championship game is far from ideal. But the 49ers looked confident on that drive to get themselves on the board.

Can the Lions now restore some breathing space?

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Jason Bell former NFL cornerback, on Sky Sports: "Christian McCaffrey is the tone setter and he's the guy they have to get the ball to. He gives them the energy.

"He wanted to bring the bring the pain and he did."

Detroit have plenty of home run hitters, but Christian McCaffrey is a one-man highlight reel and breaks off another big play with a catch and powerful run down the left sideline for 28 yards to flip the field and put San Fra into scoring position.

The Niners are across midfield and moving the ball, but it's been all about Detroit so far, with Dan Campbell's men not being intimidated on the big stage one bit.

San Francisco haven't frozen exactly, but defensively they just can't keep up with the pace of the Lions, and offensively they're quite clicking as yet.

Plenty of time to go, but Kyle Shanahan will want to see some points on this drive.

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Right then San Francisco - what have you got?

The Niners have lost the last two NFC Championship games remember, they do NOT want to lose three in a row....

And now a first touch for Amon-Ra St Brown and again it's a nice one as he takes a short catch then runs for a first down.

San Fran just have no answer for this diverse and lively Detroit attack.