Igor Akinfeev saved two penalties as hosts Russia stunned 2010 champions Spain on penalties today to set up a FIFA World Cup quarter-final with Croatia.
Croatia also required penalties after a 1-1 draw to get the better of Denmark at the Nizhny Novgorod Stadium.
Russia produced a superb defensive effort to continually frustrate their more highly-fancied opponents at the Luzhniki Stadium in Moscow as Spain seemed incapable of changing their approach.
Spain, despite a chaotic build-up to the tournament in which coach Julen Lopetegu was sacked and replaced by Fernando Hierro on the eve of the tournament, had shown enough in the group stage to suggest they were still contenders.
They dominated possession and took the lead when Marco Asensio's curling free-kick into the six-yard area hit the ankle of Sergei Ignashevich, as he tussled with Sergio Ramos, and flew into the net.
Russia hit back against the run of play when Gerard Pique needlessly stuck his hand in the air and handled an Artem Dzyuba header.
Dzyuba duly sent David de Gea the wrong way with a penalty for his third goal of the tournament.
Spain managed 1,006 passes in comparison with just 191 for Russia - a staggering difference - but created little.
Andres Iniesta came close to winning it in normal time but the deadlock remained unbroken in the extra 30 minutes.
Akinfeev denied Rodrigo in Spain's only real opportunity.
De Gea got a hand to Russia's first penalty from Fedor Smolov, but proved unable to keep it out.
Sergei Ignashevich, Aleksandr Golovin and Chernyshev all followed suit as Akinfeev saved from Koke.
Russia's goalkeeper then brilliant stopped Iago Aspas with his feet to knock Spain out.
The world's 70th ranked team were without a win in seven games before hosting the World Cup.
They will now have growing confidence of progressing further in an open half of the draw in which one of Russia, Croatia, Switzerland, Sweden, England and Colombia are guaranteed to make the final.
Croatia and Denmark enjoyed a frenetic opening in the second game of the day.
Mathias Jorgensen squeezed home from close range to give Denmark the lead in the first two minutes.
Croatia leveled just three minutes later after two deflections cannoned the ball into the path of the grateful Mario Mandzukic, who drove it into the net.
Mandzukic flicked a header wide and Ivan Perisic shot over from 10 yards but Denmark got stronger as the match progressed and came close when Christian Eriksen clipped the bar with a cross.
Jorgensen then brought down Ante Rebic after he had rounded the keeper and appeared certain to score, but Luca Modric's penalty was superbly saved by Kasper Schmeichel.
Schmeichel, watched on from the stands by his legendary goalkeeping father, Peter, shone again in the shoot-out, but so did his opposite number Danijel Subašić.
Both successfully intimidated opponents and saved with feet as well as hands, but Subašić saved three to Schmeichel's two.
Ivan Rakitic then struck the winning penalty to send a relieved Croatia through despite a below par performance.
Two more last-16 ties are scheduled for tomorrow.
Brazil will face Mexico at the Cosmos Arena in Samara while Belgium are up against Japan at the Rostov Arena in Rostov-on-Don.