Spain coach Vicente del Bosque lauded his team after securing a place at Euro 2016, but was unsure about the extent of injuries suffered by David Silva and Alvaro Morata.
Silva and Morata came off in the first half as Spain crushed Luxembourg 4-0, sealing their spot in the finals in France next year.
Del Bosque praised his side as Santi Cazorla and Paco Alcacer netted braces in Logrono on Friday.
"We made a good performance but it cost us a lot. We congratulate the qualification. We have a good team," he said.
"Our idea is to attack. We do it as a band in the middle. They are generous players in the effort."
Del Bosque thanked the crowd in Logrono, despite Gerard Pique again being jeered.
His team managed their win even after Silva and Morata came off during the first half with suspected ankle and leg injuries respectively.
"I do not know the extent of the injuries," Del Bosque said.
"Our doctors will inform you when they know something. We know nothing for now."
