La Roja's hopes of topping Group B were dented by a 2-1 defeat to Sweden on Friday (AEST), leaving it two points behind the leader having also played an extra game.
It was the first time Spain had lost a FIFA World Cup qualifying match since a 1-0 reverse by Denmark in 1993, ending a 66-game unbeaten streak.
At the midway point in the campaign, Luis Enrique believes that topping the group is out of his side's hands and has turned his focus to securing second place and a play-off berth.
Addressing the media ahead of Monday's (AEST) meeting with Georgia, the head coach said: "Football is a game of mistakes; individual and collective.
"There is no single cause as to why we lost the [Sweden] game. It's the sum of everything.
"It's no longer up to us. But it's up to us to win our own and be in the play-offs, win it and be in the World Cup.
"There are two sides. You can always improve, but I try to see the bottle half-full."
Luis Enrique also backed defender Eric Garcia, who came under scrutiny after his performance against Sweden.
"I disagree with the criticism," he said of the Barcelona defender.
"He suffered in the transitions, but also [Aymeric] Laporte, because of the conditions of the Swedes. I'm delighted with their performance."