And another.

Gabi - Atletico's captain - barks right in the referee's face after Isco bundles over Antoine Griezmann.

That is the fifth caution of the game so far.

Well, might as well get it out the way early.

Diego Godin barges into the back of Cristiano Ronaldo, briefly making his face look like that airport bust as the G-forces settle on his features.

Yellow for Godin and another for Sergio Ramos for the strength of his protests.

Those two are on a tightrope and you wouldn't bet on them both making it safely through the ninety.

Another flash point.

Antoine Griezmann is left hobbling as Casemiro slides in and makes no contact with the ball.

The Atletico players are around the referee, but he keeps his cards cool.

Probably wise. The official is going to have to use those bullets wisely.

It feels as though Atletico have bossed the opening 30 minutes. Well, they have - of course - when you look at the scoreline.

But, in terms of possession and territory, it is quite surprising to see Madrid are doing most of the running.

The visitors have had almost 70% possession, spent over a quarter of the game in Atletico's third, and made 175 passes to Atleti's 85.

But they have only managed five shots compared to the home side's eight. And are 2-0 down...

Image source, Opta

Marcelo, so good in the first leg, hits the nitro boosters and bombs on into the Atletico Madrid area.

There is a welcome committee in red and white to usher him away from goal and rob him of the ball though.

Possession is now king as the two teams each try and dictate the rhythm after a helter-skelter start.

There is still a bit of needle out there in the collisions though.

Koke hacks Luka Modric's shins as the Croatia international gets goal side of him in midfield. 

No card from the referee.

The tactical battle is more smoke and daggers now than it was at kick-off.

Three behind, Atletico had to go hell for leather.

Now, they can play it a little more canny and wait to push for a third. 

And how hard to Real search for an away goal to push Atletico's target up to five?

Penalties are never a foregone conclusion - especially if you are Atletico Madrid. And especially if you are Antoine Griezmann.

The Frenchman famously missed a penalty against Real in last year's Champions League final, and has missed two more spot-kicks in La Liga this season.

In fact, Atletico have bad form as a team from 12 yards. They have missed six of their eight league penalties this season, with Griezmann, Fernando Torres, Gabi, Yannick Carrasco and Thomas Partey all missing in the Atleti pen-go-round.

Image source, Reuters

Real Madrid must be rattled. Their once-comfortable cushion has been whittled thin inside the first quarter of the match.

They try and get on the front foot again. But Cristiano Ronaldo's first touch betrays him in the Atletico box, before Diego Godin loosens Luka Modric's fillings with a tank-like tackle.

Mark Pougatch
Presenter, BBC Radio 5 live

Didn't Griezmann hit that penalty twice? A la Zenden in the League Cup Final? So should be indirect free kick to Real Madrid?  

Rashida Qamar: O.M.G. That's a sensational start by Atletico. Best second leg I've seen in a long time! 

Briyan: The tie very much alive!

Marc Sepetowski:  Even Claudio bravo would have saved that...

Sergio Ramos heads over the top from a corner as Real Madrid look for an immediate riposte and an away-goal joker that would change the complexion of the tie once again.

There were some telling reaction shots in the wake of Antoine Griezmann's penalty - Cristiano Ronaldo looking distinctly peeved, Diego Simeone with his arms whirling like a tic-tac man on amphetamines. 

It is almost as if Atletico's blitz start has even caught their own fans out.

An eerie sense of disbelief as the home supporters, settled in for the long haul, realise they are a goal away from levelling up the tie with less than 20 minutes gone.

Pat Nevin
Ex-Chelsea winger on BBC Radio 5 live

Terrible penalty! Should have saved it!

Fernando Torres goes down as Raphael Varane sticks his foot across his path...

What has the referee given?

It's a penalty! Griezmann to take...

You can't say it hasn't been coming...

Atletico have flown out of the blocks quicker than Usain Bolt. The home side have already had six shots at the Madrid goal, with Saul finally sticking them ahead.

Image source, Opta

Conor McNamara
BBC MOTD commentator

Atletico knew they had to score early tonight and they have. 

Is the come back on?