If you support a team who are in a slump, or have done in the past, you'll recognise this from Leicester. They have gone from looking comfortable to culpable in no time at all.

They are hanging on for the half-time whistle now. 

Andy Townsend
Ex-Republic of Ireland international on BBC Radio 5 live

What a stunning finish that is from Craig Bryson. Top-class midfield play. It is a poor header from Danny Simpson but Bryson has a lot to do. There is a huge chasm in that Leicester back four and he drives into it. From 1-0 down to 2-1 in front represents a superb turnaround. They have been the best team.

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Jamie Vardy in full flight, we haven't seen that too much this season.

He leaves Bradley Johnson on his backside in midfield, races in on goal but his shot is deflected away by Alex Pearce. 

Leicester are ending the half on top, no doubt about that. Steve McClaren looks almost pained in his dugout area, hollering at full volume at someone.

He can't fault his players for effort mind, the front three are putting in mega yards to shut down the Leicester back four at every opportunity. 

And now Steve McClaren is down on the touchline, he looks sodden and freezing sans hat. Definitely the way to go.

Game's gone a bit scrappy, conditions no doubt taking a toll. Leicester go for a long throw but it's well cleared. 

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You can't keep a good man down. Darren Bent makes up for his world-class own goal with this little nod into the corner. 

Andy Townsend
Ex-Republic of Ireland international on BBC Radio 5 live

They need to be careful, Derby. They are back in the game but when their full-backs push up that is when the likes of Okazaki and Albrighton come alive.

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A colleague of mine has gone out of her way to text in and tell me off for not telling you all about Claudio Ranieri's headwear tonight.

Steve McClaren is avoiding any potential umbrella issues by staying up in the stands but Claudio is in his technical area in a nice little woolen beanie number. 

Here it is:

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Hats off to both sets of fans so far, it's a great atmosphere tonight. More away fans = better atmosphere. I think so anyway.

I read earlier that there's over 8,000 Wolves fans at Anfield tomorrow. Marvellous. 

Darren Bent is the first player to score at both ends in an FA Cup game since Aidan Hawtin for Brackley against Newport in November 2015.  

Image source, PA

Image source, PA

I'm predicting at least two more goals in this game. A fine tempo to it so far, as Will Hughes gets away from the press with two fine pirouettes one after another.

Image source, Reuters

Andy Townsend
Ex-Republic of Ireland international on BBC Radio 5 live

Great football. Lovely work from Okazaki. Derby defenders backed off and it was a good strike that Carson got a good hand on. It was almost out of nothing.

Graeme Le Saux
Former Chelsea left-back on BBC One

It's the best I've seen Leicester play for some time - and I've seen them quite a bit. The togetherness and shape, they look a lot more comfortable.

Great hands! Leicester counter attack with real verve and intent and Shinji Okazaki shoots firmly from the edge of the D, it's heading top-corner-ish and Scott Carson gets a big left hand to it to push it away. Top save. 

Chris Thompson: Bent on a hat-trick!

Liam Williams: Darren Bent has finally worked out what end he's attacking.

Carl Arrowsmith: Bent obviously loves to put the ball in the net, doesn't seem to matter which one.  

Derby are now flying as Marcus Olsson wins a corner down their left. The fans are in full voice. A good cup tie is on the boil now. 

Image source, Reuters

Graeme Le Saux
Former Chelsea left-back on BBC One

That's what you call redeeming yourself. He got to the ball first, the accuracy and direction of his header is what beat Kasper Schmeichel. There's not a lot of pace on the ball. It's an excellent header, Schmeichel had no chance.

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Andy Townsend
Ex-Republic of Ireland international on BBC Radio 5 live

That is a great finish, a classy finish. That is an experienced striker there who knows he just needs to make the right contact and let the surface do the rest. It is a beautiful glancing header. There isn't even a great amount of pace on the cross either so it needs to be placed precisely. It is exactly what Derby needed. They are right back in this and start again now.

Image source, PA