Spain's Mikel Merino celebrates following their quarter-final win over Belgium.

Mikel Merino, who smashed in the FIFA World Cup quarter-final winner against Belgium in the 88th minute on Friday, said it was "surreal" to have scored a late decider in two consecutive knockout fixtures for Spain.

"I couldn't have imagined something like this even in my wildest dreams — another goal in the dying minutes," said Merino, who had already struck in stoppage time during Spain's tense 1-0 round-of-16 victory over Portugal on Monday.

"I thought it would take a long time to repeat a feat like that... and I managed it in the very next game!"

Late in the match and with the scoreline deadlocked at 1-1, Spain's teenage defender Pau Cubarsí unleashed a low, driving shot from range.