Yup Tino Anjorin is helped off the field and he is limping badly.

Gavin Whyte replaces him.

That's the second forced substitution for Portsmouth due to injury today.

We have another injured Portsmouth player.

Tino Anjorin is down at midfield.

Looks like he has done his hamstring.

He's done.

Chesterfield are hunting for a second goal before the break.

A cross comes into the Pompey box.

It is half cleared but into the path of Michael Jacobs who sends a half volley into the ground and it bounces past some Blues defenders but finds its way into the hands of Will Norris in goal.

A chance for Portsmouth.

A high, looping cross from the far side, sails into Colby Bishop in the middle of the box.

He towers over his defender and connects with a strong downward header, but it is superbly saved down low by Harry Tyrer in the Chesterfield net.

Portsmouth's Joe Rafferty chops down a Chesterfield player on the far side inside his own half.

The first yellow of the afternoon.

Portsmouth with work to do.

10 minutes until the interval.

Can the League One leaders find an equaliser before the break?

Guy Whittingham
Former Portsmouth manager on BBC Radio Solent

Both teams want to play with the ball on the floor.

I think Portsmouth's quality is slightly overshadowing Chesterfield at the moment.

The Spireites also like to play this patient type of football but have really only had one chance so far.

Image source, Getty Images

Good save from the Chesterfield keeper Harry Tyrer to deny Portsmouth's Paddy Lane.

The winger can't find a path to cross so he goes it alone and accelerates into the box with the ball at his feet.

He shoots a low stinger from just outside the six-yard-area but Tyrer gets low and makes a strong save.

Now here come Portsmouth down the nearside.

Joe Morrell sends a low curling cross into the box, it bounces across the face of goal, but it's too long for Colby Bishop.

Good end-to-end stuff so far.

Image source, Rex Features

Chesterfield's Ollie Banks shoots from 25-yards-out!

But it is just wide.

It was a slick move from the Spireites down the nearside, Michael Jacobs with a laser-like pass across the middle, in-front of a Pompey defender and into the path of Banks.

He takes a touch, looks up and shoots but it is just wide.

Should have at least hit the target.

No goals yet but this is a decent match so far between Chesterfield and Portsmouth.

Both sides have had at least one decent chance on goal.

The non-league Spireites are having to do more of the defending at the moment.

Andrew Moon
BBC Radio Solent's Portsmouth Commentator

Chesterfield don't feel like a non-league club and crucially they are not playing like a non-league club so far this season.

Portsmouth's Regan Poole can't continue, he does look like he is in a lot of discomfort.

It's hard to tell whether it is his knee, an ankle maybe, but either way his day is done.

Sean Raggett is on.

Image source, Rex Features

Portsmouth's Regan Poole is down on the edge of the Chesterfield box.

He was really outmuscled by Will Grigg on that last exchange.

The Pompey defender looks like he is in a lot of pain.

He is up but hobbling.

Chesterfield's Will Grigg outmuscles Portsmouth's Regan Poole on the nearside edge of the Pompey box.

Passes to Ollie Banks in the middle who pops off a shot on the turn but it is saved by Will Norris.

A good move from the Spireites.

An early shot from Portsmouth sails just over the bar, but it was a good slick move from the visitors.

Terry Devlin dribbles down the far left side and fizzes a pull back pass to Paddy Lane who is just inside the Chesterfield box.

He hits it first time and it goes just over the bar.

Pompey setting the tone early.

Paul Fisher
BBC Radio Sheffield's Chesterfield Commentator

This game has got everything you need for a classic FA Cup tie.

And pitch looks fantastic despite a load of rain yesterday.

This could be a huge opportunity for Chesterfield.

A nervy start!

Straight from the kick-off, Portsmouth pass the ball back to their keeper Will Norris who is well out of his box.

He takes a heavy touch and the ball is charged down by a Chesterfield player and both end up chasing after the loose ball into the nearside corner.

Shaky stuff.

We are under way between Chesterfield and Portsmouth at the SMH Group Stadium.

Or as some people have been calling it, the Paul Cook derby.

The Spireites boss led Pompey to League One promotion in 2016-17.