As we come to the end of a very busy January for both sides, this La Liga match is the game-changer for both sides. Barcelona win this with a game still in hand and they're very definitely in the box seat but lose and the advantage is wiped out.
It's a fascinating fixture at the very best of times but this is almost as important as when Atleti won the league at Camp Nou in 2014 and Barca returned the compliment in 2015 at the Vicente Calderon.
Arda Turan up against his old side will be a particular highlight. No one will know better than the Turkish international the type of spirit that Diego Simeone's side will display during the entire 90 minutes. Let's take a look at three things that could influence the outcome of this one.
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Given how well Atletico Madrid have played under Simeone over the past few years, it's something of a surprise that the Rojiblancos have been unable to come away from Camp Nou with all three points.
Indeed, per Fussball Wettpoint, it's almost ten years to the day since an Atleti team did just that.
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One more win in Catalonia in the last 14 years is all that the visitors have to show for their energy and spirit.
But records are there to be broken and what better time than at this point in the season, giving Atleti a real fillip in their charge for another La Liga title.
There'll be swords crossed all over the pitch and each mini-battle has the potential for being the one which authors the outcome of this match.
One in particular cannot be ignored. The best that Uruguay has to offer coming face-to-face again.
In the Blaugrana corner, Luis Suarez, a striker who is in the richest vein of scoring form. Planning to stop him is none other than countryman Diego Godin, arguably the finest central defender on the planet at this moment.
Absolutely no quarter is going to be asked or given by either and Suarez will need to be at his very very best to get any change whatsoever out of Godin.
Atleti can ill afford any rash decision making from their captain, equally Godin has to be touch-tight to his countryman throughout or else Suarez will be the difference.
Attack v defence
Something's got to give in this game.
Aside from Bayern Munich, Atleti have the meanest defence in the whole of Europe.
Up against a trio that managed 180 goals in all competitions in 2015, this will be the sternest test for both.
"MSN" are expert at opening up the passing lanes, Atleti peerless in shutting the door.
A good portion of the game could well be a throwback to the "attack v defence" days of yore.
Bring it on!
What will the outcome of the game be? Have YOUR say in the comment box below!