Both FC Barcelona coach Tata Martino and Carlo Ancelotti, his opposite number in Real Madrid, have doubts regarding their respective starting 11s ahead of Saturday's Clasico between the two sides in the Camp Nou Stadium.
The game is the first time either coach has sat in the dugout for a Clasico and the result and performance of their teams could go a long way to determining how long they last in their current positions, reports Xinhua.
Barca go into the game with a three point lead over Real Madrid and the advantage of playing in front of a stadium packed with their home fans.
Martino's side has not been at its best since returning from the international break and has managed just two draws from two games, although some would argue that the 1-1 draw Barca took away to AC Milan in the San Siro Stadium was far from a bad result.
The good news for Martino is that Lionel Messi looked back to his best Tuesday night after missing three weeks with a thigh injury and Messi's will be the first name down on the Barca teamsheet, quickly followed by that of Neymar; after that there are questions Martino must answer, such as who will be the third player in attack.
Alexis Sanchez seems to be Martino's preferred choice and the Chilean has been in good form this season with his pace and workrate compensating somewhat for his lack of precision in front of the goal.
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There is also a good case for including Pedro Rodriguez, who has a habit of finding the net against Real Madrid and also for Cesc Fabregas, who can play as a false striker and whose late arrival into the penalty area is hard for defenders to close down.
Cesc's inclusion would mean there are no doubts over the regular midfield of Sergio Busquets, Andres Iniesta and Xavi Hernandez, meaning the remaining questions to be answered hang over the Barca defence.
While Dani Alves and Adriano are both certain to play as full backs, who plays in central defence depends on whether or not Gerard Pique is able to play after suffering a slight pelvic injury in Milan.
If Pique recovers he will probably partner club captain Carles Puyol, who was rested in midweek, but if Pique can't play, Martino will have to decide between youngster Marc Bartra, who has performed well in recent weeks, or the more experienced Javier Mascherano, who only returned after injury himself Tuesday night.
Ancelotti also has his doubts, but apart from Xabi Alonso, who is putting the final touches to his return after injury, he has no fitness problems in his squad.
Real Madrid look to be improving in recent games and as a result Ancelotti will keep faith with a three-man midfield, composed of Sami Khedira, Luka Modric and Asier Illaramendi, with Isco relegated to the subs' bench.
There are questions over who will play at right back with Alvaro Arbeloa likely to get the nod ahead of Javier Carvajal, although it is possible Ancelotti might decide to move Sergio Ramos across to the right and pair Rafael Varane and Pepe in central defence, a move that would add to Madrid's considerable height advantage at set pieces.
Speaking on Spanish radio Thursday night, Ancelotti hinted that Gareth Bale could start in the Camp Nou, which seems logical if Madrid want to see a return on their massive summer investment, but that decision means Ancelotti has to decide between dropping Angel de Maria or playing without a specialised center-forward.
Di Maria has responded to Bale's arrival with some of the best form of his career and his pace and ability to curl the ball in from the right would be lost if Bale replaced him in that position.
In order to accommodate both Bale and Di Maria, Ancelotti could opt to play Cristiano Ronaldo as a central striker, but has already said that would not be a good idea given Ronaldo's effectiveness cutting in from the left, or he could play Bale in a central role and leave both Karim Benzema and Alvaro Morata out of his line-up.