It didn't quite have the thrill-a-minute feel of Saturday's round if 16, but there was drama aplenty as Russian Federation and Spain battled it out in the capital.
Gerard Pique handled Artem Dzyuba's header and the Zenit St Petersburg forward sent David de Gea the wrong way for his third goal of the tournament.
There was little change in the pattern after the break, forcing coach Fernando Hierro to introduce Iniesta. The second half was played at nearly walking pace, brought very little drama - ditto the first extra time of the tournament - and Fernando Hierro's side paid dearly for their lack of ideas and intensity by exiting 5-3 on penalties in the shootout.
The 34-year-old, who scored the winning goal at the 2010 World Cup final, won 133 caps in an worldwide career spanning 12 years, during which he also won European championship titles in 2008 and 2012.
Spain were dominating possession in the first ten minutes of the encounter but they were prevented from creating clear chances by a robust Russian Federation defence.
But for all the talk of tactics and generational change, Spain's 2018 World Cup will be remembered for a simple act of self-sabotage.
Russian Federation next plays Croatia or Denmark, who play later Sunday.
"Players will not do things just because the coach says so".
Kasper Schmeichel - roared on by watching father Peter in the stands - had denied Luka Modric from the spot deep into extra-time (116) after Mathias Jorgensen had lunged in on Ante Rebic with the game tied at 1-1.
More than 74 per cent possession, an astonishing 1,137 passes and utter territorial domination, yet the only statistic that counted in the end for Spain was the two penalties they missed after they strangled themselves out of the World Cup. "We didn't play quite the way we wanted but it's hard when you don't have the ball and you spend that much time defending".
"Honestly, before the tournament I had very low expectations, everyone was just hoping to God that we would get out of the group stage".
Charged with giving false testimony for his role in a corruption case that saw former Dinamo Zagreb chief Zdravko Mamic sentenced to six-and-a-half years in prison last month, Modric's popularity has dipped despite continued brilliance on the field for his club Real Madrid and country.
Indeed, we think the general reaction to the full-time whistle was eloquently summed up by this member of the Russian team staff...
First Germany, then Lionel Messi's Argentina, followed by Cristiano Ronaldo's Portugal.
"We can't start finger-pointing at anyone and laying any blame here", he said.