Costa has come in for criticism for his lack of suitability to the playing style preferred by Del Bosque, but the Spanish national team manager is adamant the 27-year-old can function in his system.
"Our midfield is good on the ball, with players whose touch is good, so we need forwards who create space, who move, who commit defenders, occupy them, and Diego does that," Del Bosque said.
"How can Costa be harmful for us? We have him so he can get in behind, run channels, pull wide - he is not a problem for us."
"We've not had much luck with him but there's nothing that goes against our style. Now we're choosing between him, Morata and Paco Alcácer; in principle those are the three for the future."