Spain manager Vicente del Bosque has admitted that his side were poor during their 1-0 win over Croatia.
The defending champions won the game in the dying minutes through a Jesus Navas tap-in to secure their status as Group C winners.
Despite qualification to the last eight, Del Bosque feels that Spain were poor in their final group match.
"There was a lack of clarity compared with other occasions," Del Bosque said. "The truth is it was not a great game overall and this should concern us. Things didn't go according to plan.
"Our philosophy and style of play are good and we proved it in today's match. Our first touch was not so good and thanks to that we dipped in terms of speed and intensity. We suffered but then so did they. We had 17 efforts on goal to eight for them and also more possession than them.
"But Croatia played well - they did not let us play in our comfort zone, closed down the spaces and tried to hit us on the counter-attack, though we were mostly in control."
Spain will face either England, France or Ukraine in the quarter-finals.
