The Forest fans going through their repertoire of songs providing a review of the Leicester team. One of them I can't write in here. The other suggests that their top-flight status is somewhat comical on this evidence.

Martin Keown
Former England defender on BBC One

Both sets of fans are stunned at what they are seeing. Forest have flown out of the blocks. They are full of energy, full of running. Leicester - the holders - are in big trouble.

This feels a long time ago...

I'm not sure anyone in a red shirt in this ground can quite believe what they are seeing. They're absolutely loving it, though.

Martin Keown
Former England defender on BBC One

This is outstanding from Forest. It's one chance after another. It's stunning. Another set-piece and it's comical from a Leicester point of view.

Martin Keown
Former England defender on BBC One

Leicester are really suffering. They have got to get after the ball and press. This young Nottingham Forest team are really playing with confidence.

Michael Emons
BBC Sport at The City Ground

Absolute delight from the Forest fans in a crazy five-minute spell as Leicester have crumbled.

Keinan Davis, who nearly scored a sensational opener with a brilliant volley that bounced off the bar, played a massive part in the opener as his cushioned header from Brennan Johnson's cross led to Philip Zinckernagel putting the hosts one up.

That triggered the release of a smoke flare from someone among the home fans and the red smoke from that had barely cleared before Forest doubled their lead with Johnson capitalising on some woeful Leicester defending.

Forest are aiming to get into the fifth round of the FA Cup for only the second time in 17 years but are in a dream position, with their passionate fans loving every second of this. The holders are very much on the ropes.

The visitors are able to hold firm this time to head away a free-kick swung into the box from the Forest right.

The home side smell blood, though. They come again and win a corner. They want to finish this inside 30 minutes!

Leicester all over the place now. Caglar Soyuncu clumsily fouls Brennan Johnson. It's bouncing.

Talk about coolness and a bit of cheek, though. Brennan Johnson's rep is sky high. Probably just stuck another million on a potential fee.

Twenty-four seconds between the two goals I'm hearing.

Less than half a minute to light an absolute rocket under this tie.

Image source, Getty Images

Martin Keown
Former England defender on BBC One

The roof has come off the stadium!

Brennan Johnson is on to it in a flash. A lovely finish. Really clever. He takes his time and draws the keeper and it goes through his legs. Absolutely quality and it's all done at high speed.

Jonathan Woodgate
Former England defender on BBC Radio 5 Live

Absolute shambolic from Leicester. That is horrendous defending and you can see why they have conceded so many goals this season. Ridiculous from Amartey.

Martin Keown
Former England defender on BBC One

This goal is all about quality. It's floated to the back post. Really good play by Spence in the build-up as well. It might have come off Philip Zinckernagel's knee. But who cares?

Getting the best seats in the house, those pigeons.

LairdBen: Enjoyable so far but keep getting distracted by the squadron of pigeons that keep landing on the pitch

Martin Keown
Former England defender on BBC One

That was a moment of inspiration. When it comes to Keinan Davis, I'm thinking he has no right to hit it. What a wonderful effort.