Perry Ng is fortunate to win a decision from referee Darren Bond after he misjudged a header under pressure from Troy Deeney.

Deeney is not happy about the decision and runs straight into the Cardiff defender after the free-kick.

Just a talking-to for the Birmingham striker.

Jason Perry
Former Cardiff defender on BBC Radio Wales

This is the best opening eight minutes of football I've seen in a long, long time.

Rob Phillips
BBC Wales Football Correspondent

I can't think of many years watching Cardiff where you would have seen them take goal kicks like that with two centre-backs deep in their own penalty area.

Cardiff should be ahead!

It is nice work down the right once more, as Mahlon Romeo feeds Callum O'Dowda.

The Republic of Ireland international pulls the ball back for Romaine Sawyers whose shot is well saved by John Ruddy.

And the Birmingham goalkeeper gets back to his feet to also deny Max Watters' rebounded effort.

The hosts are firmly on top so far.

Jason Perry
Former Cardiff defender on BBC Radio Wales

It's great play from Cardiff, one-touch football knowing exactly where their teammates are.

Cardiff have the first real chance of the game after nice work down the right-hand side.

Mahlon Romeo and Callum O'Dowda link up well before playing Romaine Sawyers into the Birmingham area.

His back-heel falls to Ryan Wintle, who drags his shot just wide of the left post.

Scott Hogan looks to be in behind the Cardiff defence for a split-second, but the ball bounces kindly for Ryan Allsop to gather.

Michael Pearlman
BBC Sport Wales at the Cardiff City Stadium

I covered a lot of Cardiff City games last season, but this is my first match of this campaign.

Cardiff have three players in their first XI I have seen play for Cardiff before, everyone else is new.

Not unknown quantities, but how well these players blend and how quickly remains to be seen. I'm excited to find out.

Darren Bond blows his whistle and Scott Hogan gets us under way.

It is a bit warmer than ideal, but what a beautiful afternoon for football.

Image source, Getty Images

Unlike the Bluebirds, Birmingham took all three points in their last Championship fixture - a 2-1 win at home against Huddersfield.

Goals from Scott Hogan and Przemyslaw Placheta gave new Blues boss John Eustace a first win in charge.

That result came after an opening day draw against Luton Town, who finished last season in the play-off places like Huddersfield.

Michael Pearlman
BBC Sport Wales at the Cardiff City Stadium

Today we have a day Caroline Aherne would most certainly have described as "scorchio", and Cardiff are taking every step to ensure supporter safety.

Fans sat in direct sunlight - behind the goal - are being given the option of moving seats.

Good to see fan welfare being taken so seriously.

Cardiff City boss Steve Morison says he is frustrated that people are calling his Cardiff City side an unknown quantity this season.

The Bluebirds have signed 15 players this summer and had contrasting results in the Championship so far.

After beating promotion favourites Norwich on the opening day, they then let a one-goal lead slip and lost 2-1 away at Reading.

The Championship has a tough reputation for a reason.

Only one team has won both their first two fixtures - Blackburn Rovers - and just Watford, Sunderland, Hull City, Burnley and John Eustace's Birmingham picked up four points.

There's a long way to go, but here is how both sides start the day.

Image source, BBC Sport

Cardiff City are still without young winger Isaak Davies who has been the subject of interest from Burnley this week.

The Bluebirds turned down an approach, thought to be worth around £2.5m, from Burnley on Tuesday.

The versatile 20-year-old forward made 30 appearances for the Bluebirds last season.

Davies extended his Cardiff contract to 2025 when he signed a new deal in March.

Burnley have since signed Southampton winger Nathan Tella on a season-long loan, so Davies could well be staying put.

Bluebirds manager Steve Morison says Davies will face his "biggest challenge" in the wake of the rejected bid.

Image source, Huw Evans Picture Agency

Temperatures have once against soared across the UK this week, and should they reach 30C or above we will have drinks breaks this afternoon.

We are currently at 29C in Cardiff, and it will be warmer on the touchline, so we will likely have breaks today.

With temperatures set to reach as high as 37C in some parts of the country, all this weekend's Premier League games will also have mandatory drinks breaks.

Image source, Getty Images

Image source, Getty Images

There was also an early exit from the Carabao Cup for Birmingham, who were knocked out on penalties away at Norwich City.

A Jonathan Leko strike and Jonathan Tomkinson own goal saw the Blues come from two goals down at half-time to force a shootout.

But Leko and Sam Cosgrove missed their spot kicks and the Canaries progressed to the second round.

Despite the defeat, head coach John Eustace was able to hand senior debuts to Alfie Chang, Josh Williams and Jobe Bellingham - younger brother of Jude Bellingham.

Image source, Huw Evans Picture Agency

Just one of Cardiff's starting XI against Portsmouth - Jaden Philogene as we've just noted below - has retained his place for this afternoon's Championship match.

To offer an opportunity to those who had not featured yet, manager Steve Morison made 10 changes in midweek and handed debuts to three of his 15 summer signings.

But after their 3-0 defeat to lower league opposition, Morison said the poor performance made his selection for today "really easy".

"No-one can sit there and say 'I should be playing'," said Morison.

"That goes for the players who played on Saturday [in the defeat at Reading] as well, so I get a free hit selection-wise."

John Eustace has made one change from their Championship win over Huddersfield last weekend.

Alfie Chang, who made his first senior start against Norwich in midweek, replaces Ryan Woods - who has joined Hull City.

Dion Sanderson returns to Cardiff having spent the second half of the 2019-20 season on loan with the Bluebirds.

Jobe Bellingham, younger brother of England international Jude, is on the bench for the Blues.

Birmingham: Ruddy, Colin, Sanderson, Trusty, Roberts, Placheta, James, Chang, Bacuna, Hogan, Deeney (C).

Substitutes: Etheridge, Friend, Williams, Bellingham, Leko, Hall, Jutkiewicz.

Image source, Getty Images

Steve Morison has made two changes from their last Championship match away to Reading.

Defender Perry Ng returns from suspension in place of Curtis Nelson, while there is a first league start for Jaden Philogene.

The Aston Villa loanee is the only player to remain in the starting XI from Cardiff's midweek defeat to Portsmouth.

Cardiff: Allsop, Romeo, Ng, Kipre, Collins, Rinomhota, Wintle (C), Sawyers, O'Dowda, Philogene, Watters.

Substitutes: Alnwick, Simpson, Ralls, Ojo, R Colwill, Harris, Etete.

Image source, Huw Evans Picture Agency