Spain manager Vicente del Bosque has praised his team's fighting spirit after they topped Group C at Euro 2012 following a 1-0 win over Croatia.
The defending champions were frustrated by their resilient opponents for large periods in Gdansk, before second-half substitute Jesus Navas struck the only goal of the game with two minutes remaining.
"It was a difficult game for us. We had a high percentage of ball possession and we proved we can control the game," said Del Bosque. "We were fighting for a victory, not a draw, and we have taken a step forward here by qualifying. This is motivation for the quarter-finals.
"The team played well, even though things didn't go according to plan. It was a very tense match, very tough. They closed ranks at the back very well and didn't give us much space.
"We threw on Cesc [Fabregas] because we needed not only possession of the ball but someone to get forward into goal scoring situations."
Spain will now face the runners-up from Group D in Donetsk on Saturday.