The Association of Spanish Footballers have confirmed that the Racing Santander players still plan to boycott Thursday's Copa del Rey clash.
Santander captain Mario Fernandez announced on Monday they would refuse to take the pitch against Real Sociedad if the current board remain in place.
The players cited four months of unpaid wages as the reason for their decision, and called for the club's president Angel Lavin to step down.
Santander go into the second leg 3-1 behind but the deciding tie may not get started as the players union (AFE) confirmed the strike would still go ahead unless their demands were met.
"If at 2100 (CET) the Racing board is the same as now, they (the players) will not play," AFE president Luis Rubiales confirmed having met the squad.
"The squad decided something last Monday which they made public, and they continue thinking exactly the same, that if the current board have not resigned by the time of the game they are not going to play.
"They have the complete backing of the AFE, as always."
The players were warned that not competing could have implications regarding the competition, but Rubiales expects them to remain defiant.
FIFPro, who represent players on a global scale, also backed the players' cause.
"FIFPro supports the fundamental rights of the players to have their contracts respected. That they should expect to receive their salary each month is non-negotiable," they said in a statement.
"AFE is digging deep to provide the players of Racing Santander with temporary financial support. It will provide one month's salary from its emergency fund to help all concerned buy a little extra time while they continue to fight for their outstanding wages."
|Man City arrivals have brought trophy hunger back - Kompany|
|Better than Suarez & Van Persie: Opta stat proves West Ham have a bargain in Hernandez|
|Wolf signs on with promoted Stuttgart|
|Striker Hernandez completes £16m West Ham switch|
|Lukaku reveals how Pogba talked him into Man Utd move|
|Morata: It was my destiny to play for Conte|
|´All good!´ - Keita and Demme make up after Leipzig spat|
|Bernardeschi joins Juventus for €40m|
|Wolfsburg out of race for AC Milan´s Suso|
|Cassano delivers third U-turn in baffling week to confirm retirement|
|Bailly to miss Man Utd´s Super Cup clash with Real Madrid|
|Riedewald reunited with De Boer at Crystal Palace|
|Neymar ´would be welcome´ at Real Madrid, jokes Casemiro|
|James & Ancelotti back Morata for Chelsea success|
|I don´t think Pique was joking – Alba confident Neymar will stay|
|Maldini hails Bonucci capture and backs Milan for Champions League challenge|
|RB Leipzig´s Demme escapes serious injury after reported Keita bust-up|
|Inter 1 Lyon 0: United target Perisic impresses as Jovetic nets winner|
|Leaving so soon? Cassano the latest in football´s long list of short stays|
|You´ll miss me! – Mbappe bids farewell to new Manchester City signing Mendy|
|I always wanted Manchester City, says new signing Mendy|
|Cassano quits Verona as saga takes another twist|
|Manchester City spree continues with Mendy arrival|
|Dortmund rule out selling Sokratis to Juventus|
|Milan coach Montella hopes Scudetto can become ´a concrete goal´|
|Martial is a defender´s nightmare, says Lingard|
|Pedro suffered facial fractures, Conte confirms|
|Bale gunning for more Real Madrid success as United speculation ends|
|Ancelotti rules out Vidal sale, Sanches departure ´a possibility´|
|Van Dijk left out of Southampton´s pre-season trip|
|Bernardeschi attends Juventus medical ahead of €40m switch|
|Bayern president labels big spending ´a sign of weakness´ amid Neymar rumours|
|I sent 10 messages a day - Montella pestered Milan chiefs to attempt Bonucci coup|
|Defoe dreaming of World Cup call-up|
|MLS Review: Timbers, Sounders claim important conference wins|
|Mexico 0 Jamaica 1: Late Lawrence stunner sinks defending champions|
|Vardy: I have no regrets after turning down Arsenal|
|Conte believes Fabregas could be key for Chelsea|
|Blanc: Difficult for Verratti to leave PSG|
|Mourinho praises Martial but wants consistency from United star|
|Morata backed for Chelsea success by Spanish duo|
|Zidane: I haven´t asked for a forward amid Mbappe links|
|Henry: Messi´s development not yet over|
|De Boer compares Zaha to Neymar|
|Neymar could take PSG to next level – Blanc|
|Real Madrid 1 Manchester United 1 (1-2 pens): De Gea proves his worth to Mourinho|
|Belotti scores in Torino win, Terry lifts bizarre Cup of Traditions|
|PSG cannot get Sanchez so they go for Neymar - Wenger|
|De Rossi: Juventus have no weaknesses|
|He´s staying - Pique eases Barcelona fears over Neymar|
|Bordeaux to sign Arsenal flop Wellington Silva|
|Markovic free to leave Liverpool, says Klopp|
|WATCH: Insane hailstorm leads to friendly cancellation|
|Terry lifts bizarre trophy as Aston Villa claim Cup of Traditions crown|
|Kolarov: Lazio was a good experience, but they are my rivals|
|Dybala not worth as much as Neymar - Chiellini|
|Ronaldo: Being better than Messi is my motivation|
|Lahm named German Footballer of the Year 2017 after retirement|
|Danilo sets out Man City Champions League ambition|
|Neymar will stay at Barcelona, insists Marlon|
|Cahill named new Chelsea captain by Conte|
|Kenedy ´strongly reprimanded´ as Chelsea apologise again to people of China|
|Klopp expects Can stay after ´good talks´ over new Liverpool contract|
|Perisic can leave if Manchester United make serious offer – Spalletti|
|Shaw, Young and Rojo have ´no chance´ for start of new season|
|Rooney one of the best in his position - Koeman|
|Leaving on a jet plane - Mendy flies off to LA as Man City move nears|
|Bilic hails arrival of ´massive player´ Arnautovic|
|Bosz: Aubameyang to China talk is ´nonsense´|
|El Salvador´s Romero banned for biting Altidore|
|Real Madrid defender Danilo joins Manchester City|
|Pedro travels home after suffering concussion|
|MLS Review: Villa, New York City end Chicago run as Dallas go top|
|Costa Rica 0 United States 2: Dempsey equals Donovan record in win|
|Valverde: Barcelona must keep Neymar|
|Paris Saint-Germain 2 Tottenham 4: Eriksen, Alderweireld score stunning goals|
|De Gea definitely staying at Man United – Mourinho|
|Mourinho rules out United move for Bale|
|Juventus 1 Barcelona 2: Neymar shines with superb brace|
|Rooney scores again for Everton as Sevilla are shocked|