The Chelsea forward was left in the cold for the clashes against Luxembourg and Ukraine, but his national team-mate insisted that with patience he would find his way back.
Juan Mata has defended Diego Costa's form for Spain after the striker was left out of the national squad and replaced by Alvaro Morata for the upcoming Euro 2016 qualifiers.
Costa is suspended for the game with Luxembourg on October 9, but the 27-year-old would have been available to face Ukraine in Kiev three days later.
Head coach Vicente Del Bosque insisted the Chelsea striker was only left out because of his ban for one of the two games, but he has struggled since pledging his allegiance to Spain over Brazil, scoring once in nine caps.
Manchester United star Mata, though, has sympathy for the tough task Costa faces as part of a Spain team that plays with a slow, passing style.
"Being the striker in a team like ours, with so many midfielders, is not easy," the playmaker told.
"You have have to adapt and above all be patient, because there is a lot of time without touching the ball. But when you do get it you have to finish well. It is a very complicated role and players like [David] Villa or [Fernando] Torres did it very well, but it is difficult to come in and adapt.
"It is very difficult to face him. I would rather have him as a team-mate than a rival. His movement and goals will always create problems. Also because he fights with the centre-backs and causes friction that somehow knocks the opponents' concentration."
Costa has been a target for significant criticism in England, particularly since his clash with Arsenal defenders Laurent Koscielny and Gabriel which eventually landed him a retrospective three-match suspension.
Mata again defended his international team-mate, saying that aggression has always been part of Costa's game.
He continued: "That is his game and always has been - it is not new. Now it seems to be talked about more because he is in the Premier League and he is something different from what was there, but he has always played well."