Clayton is ok to continue, but it looks like Gardner's race is run.

He goes down clutching his right hamstring.

There's a break in play as Blues midfielder Adam Clayton needs treatment after a clash with Jason Knight.

Birmingham's Gary Gardner is also struggling with injury.

After using four subs at half-time, Aitor Karanka doesn't have much wriggle room in terms of replacements.

Louie Sibley lets fly at goal once more.

This time it's a left-footed half-volley from inside the area after pouncing on a loose ball, but it's off target.

The Derby forward has been a real threat this evening.

Gary Gardner picks up a deflected cross on the edge of the box, swivels and shoots.

His low effort goes through the legs of Derby centre-back Andre Wisdom and whistles narrowly wide of the left-hand upright.

We've got just under 10 minutes left in Stevenage's game with Cambridge.

Can the EFL's bottom club hold on? They're still leading 1-0 against the play-off chasing U's, and a win will take them to within two points of safety.

In League One, Burton's crucial tie with Wigan has got started. It's 24th vs 23rd in Staffordshire with both sides desperate for points.

It's goalless after 10 minutes.

It's been a low key start to the second half.

No signs of a revival for Blues so far, and they have a lot of work to do.

Four substitutions at the break is... bold.

It looks like Kristian Pedersen might have been slightly injured as he hobbled off after initially lining up for the second half.

Can the new players inject some purpose into this Blues side?

The visitors get the second half started.

Derby are in complete control of this match, but can Birmingham mount a comeback?

There's a quadruple change by Aitor Karanka at the break, with Jake Clarke-Salter, Mikel San Jose, Jonathan Leko and Lukas Jutkiewicz all coming on.

Kristian Pedersen, Ivan Sunjic, Jeremie Bela and Scott Hogan are the men replaced.

A reminder there are eight more Championship games to come this evening. Here's what else is in store:

• Sheffield Wednesday v Middlesbrough (19:00 GMT)
• Huddersfield Town v Blackburn Rovers (19:45 GMT)
• Luton Town v Bristol City (19:45 GMT)
• Norwich City v Queens Park Rangers (19:45 GMT)
• Preston North End v Coventry City (19:45 GMT)
• Rotherham United v Barnsley (19:45 GMT)
• Wycombe Wanderers v Cardiff City (19:45 GMT)
• Stoke City v Nottingham Forest (20:00 GMT)

Image source, Rex Features

The second Championship game of the day comes in Yorkshire.

Sheffield Wednesday's rollercoaster 2020 took another turn late on Monday night when they sacked boss Tony Pulis after just 10 games (and one win) in charge.

Pulis' brief stint at Hillsborough capped off a pretty miserable 12 months for the Owls.

They entered the year in a play-off place but dreadful form until the lockdown in March - and indeed after football restarted - left them sweating over their place in the division.

They started the 2020-21 season with a 12-point penalty, reduced to six, for breaking EFL spending rules and Garry Monk was sacked in October.

Pulis was appointed to steer them away from danger but they start tonight's game three points adrift of safety.

The managerless Owls host a Middlesbrough side who are in good form and are well rested after their Boxing Day game at Rotherham was called off because of positive Covid-19 tests in the Millers camp.

Neil Thompson has been placed in caretaker charge of Wednesday.

In League Two, three games are off. Leaders Newport County's fixture with Exeter City has been called off because of a waterlogged pitch at Rodney Parade.

That gives Forest Green Rovers the opportunity to seize top spot if they beat Crawley.

Elsewhere, a positive Covid-19 test in Morecambe's squad means their match with Bolton has been postponed and Mansfield's game with Salford is unable to take place following heavy snowfall in Nottinghamshire.

Bottom club Stevenage still lead Cambridge, with just under 25 minutes left at the Lamex Stadium.

• Stevenage 1-0 Cambridge United (L)
• Bradford City v Port Vale (19:00 GMT)
• Forest Green Rovers v Crawley (19:00 GMT)
• Grimsby Town v Oldham Athletic (19:00 GMT)
• Leyton Orient v Southend (19:00 GMT)
• Newport County v Exeter City (19:00 GMT)
• Walsall v Scunthorpe (19:00 GMT)
• Barrow v Tranmere (19:45 GMT)
• Colchester United v Cheltenham Town (19:45 GMT)
• Harrogate Town v Carlisle United (19:45 GMT)

Away from St Andrew's, seven League One fixtures this evening have been called off, all because of positive Covid-19 tests.

Doncaster Rovers are the latest club to postpone upcoming matches after three of their players tested positive for coronavirus.

That means we've got just five third-tier matches for you tonight, with the bottom four all in action:

• Burton Albion v Wigan (18:30 GMT)
• Swindon Town v MK Dons (19:00 GMT)
• Northampton Town v Gillingham (19:45 GMT)
• Plymouth Argyle v Oxford United (19:45 GMT)
• Shrewsbury Town v Blackpool (19:45 GMT)

Image source, Rex Features

Derby in complete control at the break after the Birmingham defence imploded and gifted them three goals.

Krystian Bielik, Graeme Shinnie and Colin Kazim-Richards have all netted for the Rams.

And it could have been more for the visitiors.

The Rams threaten again from successive corner.

Matt Clarke rises highest both times but is denied - first by the outstretched leg of Adam Clayton.

Then Neil Etheridge gathers his header on his goalline at the second attempt.

Almost a fourth for the visitors.

Kamil Jozwiak advances on the Blues defence and plays in Louie Sibley on the left hand side of the box.

The angle is against the forward but he sees his shot deflected into the sidenetting by Maxime Colin.

The end product is really lacking for the Blues, as Jeremie Bela is wayward with his delivery once again.

The hosts are four games without a win and will find themselves dragged into the relegation scarp if they don't arrest their slide soon.

In a rare Birmingham attack, Gary Garnder flashes a cross into the Rams box from the right.

Scott Hogan can't get on the end of it before Jeremie Bela picks up the pieces on the far side.

But, after a bit of trickery to try and beat his man, Bela then sends his cross behind.

Can Birmingham find a way back into the game before the break?

Derby interim boss Wayne Rooney will be fairly pleased with his side, who are looking composed when they have possession.

The points are theirs to lose now.

Derby County had scored 10 league goals before this evening.

Now they have three in the first half-hour tonight.

The last time the Rams scored three, I hear you ask?

In a 3-1 win at Birmingham, on the last day of last season.