Although Casillas is first choice for his club in the King's Cup and Champions League, Diego Lopez has played in goal throughout the BBVA Primera Liga campaign. (Agencies)
Speaking in an interview, Casillas said he believed the situation should remain as it is until the end of the season.
"Diego deserves support, he has started one competition and I hope he should finish it. It is a question that has got a bit boring. If the coach has given his support to Diego in the league and to be in the Cup and in Europe, that's fine," said Casillas.
The knee injury suffered by Barcelona's keeper Victor Valdes means there is now a third goalkeeping place up for grabs in the Spain squad for this summer's World Cup in Brazil.
Although Manchester United's David de Gea looks likely to get the nod from Spain coach Vicente del Bosque, logic dictates Lopez must also be a candidate.
"Of course he is," commented Casillas.
"Vicente has picked him for the national team in the past, but it is a decision he has to take. Following Victor Valdes' injury, he will have been following other keepers and he will select the one he believes is best for Spain,” he added.
Although Casillas said he accepted the current situation, earlier in the season he also hinted he could seek to move to a different club if things were to remain the same next season, but he avoided questions over a possible move to the Premier League.
"There are always rumours, but my hope and wish is to see out my contract. The main thing now is to see out the season and to try and enjoy it," said Casillas.
Although Casillas is first choice for his club in the King's Cup and Champions League, Diego Lopez has played in goal throughout the BBVA Primera Liga campaign.