The key questions for Atletico as soul-searching begins after RB Leipzig loss

As Atletico Madrid's latest Champions League let-down - Thursday night's 2-1 loss to RB Leipzig - sinks in Sportsmail looks at the fall-out.

Does quarter-final defeat spell the end for Diego Costa and for Arsenal's chances of landing Thomas Partey? Will Diego Simeone change?

And will Joao Felix build on his performance to really arrive next season?

IS SIMEONE IS STILL THE MAN?

Well, he was after Atletico knocked out Liverpool. And he was when he got them into the Champions League places when it seemed, going into lockdown, that they were bound for Europa League at best.

'Whoever objects to his selection let them buy their own club so they can pick the team themselves,' was Atletico president Enrique Cerezo's dramatic response to some mild criticism of the manager on Friday.

Most supporters back him still. What is clear is that after two seasons of talking about the club being in a transition period next season he will need to challenge Barcelona and Real Madrid and go again in the Champions League.

The greatest argument from Simeone's supporters is: where were they before he arrived eight years ago?

They were watching all of the Champions League on the television. Now they get knocked out in quarters and some call it a bad year.

COSTA'S LAST STAND?

He spent most of Thursday night in Dayot Upamecano's pocket and it was another reminder that the Brazilian is no longer capable of monstering defences single-handedly as he once did.

The physical decline of a striker doesn't matter if he still scores goals, but Costa has scored five times this season.

AND MORATA'S NOT THE ANSWER EITHER

When Morata replaced Costa, Upamecano's night didn't get any more complicated.

There was one moment when the Atletico substitute went up for a header with the Leipzig defender and he seemed to be cleared along with the ball.

He has 16 goals in all competitions which is better than Costa but still not enough.

Diego Simeone wanted to buy a striker last summer and again in January but both times was frustrated by lack of funds.

Maybe Atletico don't need to break the bank – an Ante Budimir or even a Chimy Avila might be within the budget. They need goals.

THOMAS PARTEY MUST BE RENEWED OR REPLACED

Never has a game shown how important Partey is to Atletico.

Would they have been bullied in that first 45 minutes had he been on the pitch instead of on the bench not 100 per cent fit.

His 50million euros release clause remains a bargain even in the post-pandemic market. Simeone needs to renew the 27-year-old and build his midfield around him.

Or if he really doesn't fancy him, then Atletico need to make sure they get the full release clause for him be that from Arsenal or from Juventus and bring in a replacement.

WHAT ABOUT JOAO FELIX?

Simeone was criticised for not playing the Portuguese for the entire game after he did more as a substitute than anyone else had done in the previous 58 minutes.

In the Atletico coach's defence the record signing has found his first season tough physically and there are no guarantees that had he started the game he would not have been swept away by Leipzig's relentless intensity just as his team-mates were.

As it was he came on when the tempo had dropped and spaces were appearing. He is clearly a massive talent.

It's a challenge for Simeone to prove that the 20-year-old did not go to the wrong club when he went to Atletico.

He did it with Antoine Griezmann, he has to do it with Joao Felix.