The European champions have been lauded for the quality of their slick passing game and possession football, but there was less evidence of it in a hostile Istanbul as they were put under constant pressure by the Euro 2008 semi-finalists.
Semih Senturk gave the Turks the lead in the first half of Wednesday's match and it took a 63rd-minute penalty from Xabi Alonso and a stoppage-time strike from Liverpool team mate Albert Riera to seal Spain's sixth win from six in Group Five.
"The three points are important because they were won in a difficult stadium and it's true some days you win better than on others," Casillas was quoted as saying in sports daily AS on Thursday.
"People will respect us more for games like these."
Spain moved six points clear of Bosnia, and 10 ahead of third-placed Turkey with four matches left to play, and have equalled their best unbeaten run set by coach Javier Clemente between 1994 and 1998 going 31 games without defeat.
"We have proved we have a winning mentality, that we grow in adversity, and when things aren't working well for us we resort to motivation and ambition to get there," defender Carlos Marchena said.
Coach Vicente del Bosque praised the players for refusing to settle for a draw: "It's a very positive sign. We are on a winning roll and we have to make the most of it."
Turkey have a steep hill to climb if they are to make it to the South Africa finals next year with their only realistic hope being to overhaul Bosnia for the playoff place in the group.
"This could have been a historic night for Turkish sport, not just Turkish football. The team let this slip," coach Fatih Terim said.
"Our fixtures are not easy but the Turkish national team is capable of beating anyone, anywhere. Bosnia have the advantage now, we have to accept this."
