Akinfeev saved Koke's and Iago Aspas' spot kicks after both teams had scored two apiece in what was Russia's first ever World Cup penalty shootout, to send his team to the last eight after a lacklustre 1-1 draw over 120 minutes.
The excitement of the first half dissipated soon after the restart as the game fell into a rather tiresome rhythm of Spain dominating possession without truly threatening.
Russia's Artem Dzyuba celebrates scoring on a penalty against Spain in the round of 16 World Cup match at the Luzhniki Stadium in Moscow on Sunday.
Spain dominated the possession in the opening minutes, as plenty expected, but it was Russian Federation that had the match's first semi-dangerous chance.
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In the shootouts, it was Akinfeev who emerged as the hero, first diving right to keep Koke's effort out, before denying Aspas with his feet, as the World Cup witnessed yet another fairytale and Russian Federation 2018 lost one more of the so-called pure-bred teams.
Despite 75 percent possession, Spain's famed tiki-taka passing game rarely carried them into the box and they had to wait until the 85th minute to test Akinfeev with a low drive from substitute Andres Iniesta. The Russia defender was in the process of bundling Sergio Ramos over from a free-kick when the ball hit the back of his leg and deflected in.
They looked, however, equally toothless up front, with Aleksandr Golovin's curled effort their only noteworthy opportunity until Gerard Pique's handball gave them a chance to level with a penalty in the 42 minute.
A stodgy Spain could not break the hosts down and were denied a penalty following a VAR review in extra-time, sending the tie to a shoot-out.
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We have had such great reliability for so many years and as painful as it is, we have to take the rough with the smooth. As always, he was brutally honest with himself and with everyone and we could have all done a better job this weekend.
But Stanislav Cherchesov's Russian Federation, gathering strength from its fans in the capital city, ensured a gladiatorial battle to wrest an unbelievable win against one of the tournament favourites Spain.
However, Iniesta's effort was parried away by Igor Akinfeev and extra time was called in Moscow.
The game - nearly inevitably - went to extra time with both teams continuing where they had left off and Dani Carvajal could have perhaps done better when meeting a cutback from Aspas.
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