Time to take a look at the couple of games we've got coming up at 14:00 GMT...

Lee Turnbull
Former Chesterfield striker on BBC Radio Sheffield

Chesterfield have got a little complacent these last few minutes.

They should take the last few minutes as a warning sign.

Portsmouth are top of League One for a reason.

This game is far from over.

Chesterfield make a double switch to shore up the midfield and defence.

Armando Dobra and Branden Horton are off.

Mike Jones and Sheffield United Miguel Freckleton are on.

Chance for Portsmouth!

Paddy Lane whips in a beautiful curling cross with his left foot from the nearside.

The box is rammed with blue and orange shirts (hard to tell exactly what colour Pompey are wearing) and the ball lands for the sub Abu Kamara.

It is low and he squats to angle his header on goal, but it is a bit soft and is easily saved.

Should have volleyed it?

Lee Turnbull
Former Chesterfield striker on BBC Radio Sheffield

Portsmouth look a bit ragged now.

It's been a bit of a nightmare for them so far today.

But this is a great game, a really good game.

Portsmouth are caught out and robbed of possession in their own half.

Chesterfield's Michael Jacobs and Armando Dobra both involved and are allowed to charge on goal.

The hosts get a shot away but a chasing Pompey player does enough to disrupt the effort and it is cleared.

Image source, Rex Features

Terry Devlin and Jack Sparkes are off for Portsmouth.

Abu Kamara and Kusini Yengi is on.

Forgot to mention this one at the half too, apologies, Joe Rafferty was also taken off and Zak Swanson.

Andrew Moon
BBC Radio Solent's Portsmouth Commentator

You get the feeling that Pompey are just clinging on to this game at the moment.

The Chesterfield free-kick floats into the Portsmouth area.

But no one is home and it is cleared.

Both teams have come out this second half full of energy.

End-to-end stuff.

Chesterfield defender Liam Mandeville goes down and he has won a free kick from a dangerous spot.

The ball is placed on the edge of the Pompey box.

We know how good the Spireites can be from these kind of set pieces.

Paul Fisher
BBC Radio Sheffield's Chesterfield Commentator

Chesterfield have looked so comfortable so far in this game.

Guy Whittingham
Former Portsmouth manager on BBC Radio Solent

Portsmouth have to be careful committing players forward here.

Nearly caught out there.

Pompey on the break but it is well defended by Chesterfield midway into their own half.

Now here come the Spireites in the other direction.

Ollie Banks receives the pass in the middle just outside the Pompey box but his right footed shot is weak and easily saved.

That is the third time today he has been unable to get a decent shot off despite having time.

Lee Turnbull
Former Chesterfield striker on BBC Radio Sheffield

Chesterfield are looking really good.

Excellent play by Michael Jacobs again who has been outstanding today.

Chopping and chopping around defenders.

Chesterfield start the second half just like they did the first, full gas and on the attack.

Michael Jacobs is allowed to dribble between and around Portsmouth defenders, at will.

He shoots but his shot is deflected.

Four ties remain this afternoon. Here's what's coming up...

• Kidderminster Harriers v Fleetwood (14:00 GMT)
• Slough Town v Grimsby (14:00)
• Crewe v Derby (14:45)
• Charlton v Cray Valley Paper Mills (17:30)

Plus we've got the draw for round two at 14:30. You won't miss a thing if you stick here with us!

Paul Fisher
BBC Radio Sheffield's Chesterfield Commentator

Image source, Rex Features

It has been a pulsating FA Cup tie so far.

This is what the competition is all about.

Image source, Getty Images

Chesterfield on top thanks to a Tom Naylor header on the 32nd minute.

Portsmouth look strong but have been forced to make a couple of substitutions due to injury.

It's the National League leaders out in front against their League One opponents.

Chesterfield threatening again.

Ollie Banks collects on the edge of the penalty area in a central position.

Works the ball on to his right foot and shoots, but it's not quite powerful enough, and is comfortably saved by Will Norris in the Pompey net.

Five minutes of added time.

Chesterfield have looked really impressive these last 15 minutes.

Pompey have had their chances though.