Atletico Madrid can move eight points clear of Real Madrid by beating their city rivals on Sunday in a much-anticipated derby that could go a long way to deciding La Liga's title race.
Atletico sit five points ahead of Real Madrid and Barcelona, with a game in hand over both, making defeat for Zinedine Zidane's side this weekend almost unthinkable if they want to stay in the race at the top.
After consecutive slip-ups against Levante last month and then a Champions League loss against Chelsea, Atletico suddenly looked vulnerable to the resurgent chasing pack.
But a hard-fought win over Villarreal last weekend steadied the ship while Real Madrid surrendering two points at home to Real Sociedad delivered an unexpected boost, shifting the momentum again ahead of the duel between first and third.
Atletico were beaten 2-0 by Real Madrid back in December, their one loss sandwiched between 15 league victories as Diego Simeone's team paid the price for a hesistant performance at Valdebebas.
A similarly reactive display prompted the defeat to Chelsea in the Champions League.
Whether Atletico are given the license to attack Madrid and have the belief they can beat them could be crucial to their chances of taking a huge step towards winning their first league title since 2014.
"We want to show why we're top of the league," Luis Suarez told La Liga TV this week. "This is a very ambitious team."
Suarez has scored 16 goals already this season but has gone four games now without, even if the Uruguayan will be among those happiest to see the return of Kieran Trippier on the right.
Trippier is expected to start after serving his ban for breaking betting regulations, with Atletico struggling to find a replacement for his creativity during his absence.
Real Madrid have an attacking problem to solve too, unless Karim Benzema can spring a surprise by recovering from injury in time to feature.
"Karim can be with us and the idea is that he will be but he hasn't trained yet," said Zidane on Monday.
Benzema's back-up Mariano Diaz is also out while Luka Jovic was allowed to rejoin his former club Eintracht Frankfurt in January.
In their absence, Zidane may have to deploy a front three without a recognised striker. Isco, Vincius Junior, Rodrygo or Marco Asensio could all be given the job of a floating centre forward.
Barcelona will benefit whatever the result in Madrid, as long as they can win away at Osasuna on Saturday.
Gerard Pique had said reaching the Copa del Rey final would "change everything" for Barca this season and after coming back from 2-0 down to beat Sevilla after extra-time on Wednesday, a trophy is now within reach.
Some are even wondering if Ronald Koeman's side could yet win the double, with Atletico still to visit Camp Nou in May.
Success in the league or cup would boost Koeman's case for staying under Barcelona's new president, who will be voted in on Sunday following a turbulent year for the club.
"I have a contract," said Koeman on Tuesday. "When we know who is going to be the president of course we will talk and I want him to show me where he wants to take things."
Valencia v Villarreal (2000)
Real Valladolid v Getafe (1300), Elche v Sevilla (1515), Cadiz v Eibar (1730), Osasuna v Barcelona (2000)
Huesca v Celta Vigo (1300), Atletico Madrid v Real Madrid (1515), Real Sociedad v Levante (1730), Athletic Bilbao v Granada (2000)
Real Betis v Alaves (2000)