Iceland could hardly get out of their own half with five minutes to go and were desperately defending for their lives. Missing the penalty hurt.
No Iceland defender was at fault for failing to stop Aguero's goal.
VAR has been used to varying degrees of success in Serie A and the German Bundesliga, while Federation Internationale de Football Association used the system at the Confederations Cup in Russia a year ago. Birkir Bjarnason had already sidefooted narrowly wide as a deflected cross scooted untended across the box, and the Alfred Finnbogason equalizer came after Argentina had three times failed to clear balls fired across the box.
Argentina were much smoother on the ball, as to be expected when a team contains players the calibre of Lionel Messi, Sergio Aguero and Angel Di Maria, but there were plenty of warnings signs as well.
Messi's miss Saturday was his fourth missed penalty in his last seven attempts for Argentina and Barcelona.
With the pair lacking the mobility to properly shield an already vulnerable back-four, and neither offering the passing ability to make up for it, Argentina's prospects of a long stay in Russian Federation appear to rest nearly exclusively on Messi and company outscoring their opponents. Seldom threatening to take the lead itself, Iceland also shut down Argentina's efforts to win the game. In the absence of Messi's sparkle, Argentina's attack was a bit flat and they need to improve on that if they are to live to their high expectations.
And he's revealed he KNEW where Messi would put his penalty, having swotted up in the build-up to his country's first-ever World Cup match.
Argentina boss Jorge Sampaoli denied suggestions he was underestimating Iceland after naming his starting XI for Saturday's World Cup clash in his pre-match press conference.
Iceland sits deep and packs the center, and when there is no space it is very hard for anybody to play.
It's worth noting that nearly two years ago to the day, Iceland took on another world-class striker at Euro 2016 who ended up with a similar stat line to Messi's: 10 shots, one on target, no goals.
This encounter will be the first between both teams but they still have two other teams in Group D to contend with as Nigeria and Croatia face-off in the late kick off set to be played in Kaliningrad.
"I hope that the Croatia game can be better".
Ronaldo criticized Iceland the same way after Portugal's 1-1 draw in Iceland's Euro 2016 debut.
"It's not the best feeling", Argentina's record appearance holder said. The world's most popular sporting tournament is back in Europe for the first time since it was hosted by Die Mannschaft's nation dating back in 2006.
But they were massively outnumbered in the 45,000-capacity stadium by Argentina fans, and Iceland coach Heimir Hallgrimsson did not understand why. "They probably would open a little bit more and we could get more space".