The Saudis ended a dispiriting run of 12 World Cup matches without a win, recording their first victory at a finals since 1994 with a last-gasp victor from Salem al-Dawsari.
At the same time in Saransk, Paraguay official Enrique Caceres was persuaded to give Iran a penalty for handball by Portugal's Cedric Soares that could hardly be considered deliberate.
Iranian goalkeeper Alireza Beiranvand's save to deny Ronaldo was the fifth instance of a player failing to convert a penalty in Russian Federation, already the joint second highest in World Cup history.
Their Portuguese coach Carlos Queiroz, a self-described "bad loser", was incensed by the result, teeing off at the refereeing and renewing his attack on the VAR system that he said had let Cristiano Ronaldo off the hook for an elbow to the face.More news: Australia out of World Cup as Carrillo and Guerrero strike for Peru
That said, this World Cup would be on course to beat the tally of 18 eventually even without VAR.
Spain drew 2-2 with Morocco to top Group B thanks to a late Iago Aspas equaliser that was referred to the video assistant referee and Iran held Cristiano Ronaldo's Portugal to a 1-1 draw.
Portugal will be hoping not only to win but to produce a performance more convincing than the turgid fare they produced in Wednesday's 1-0 win over Morocco. The previous holder of the record for Portugal was Cristiano Ronaldo (33 years, 135 days), when he scored the victor against Morocco.
However, they can still play a huge role going into the final fixture as Spain, Portugal and Iran are all still susceptible to facing an elimination.More news: Apple releases iOS 12 Public Beta
Combine that with a defence that's kept three clean sheets and Edinson Cavani and Luis Suarez both among the goals and, suddenly, Uruguay look a lot more formidable.
Ronaldo missed the chance to join them, having scored the tournament's first penalty in Portugal's 3-3 draw with Spain.
In Brazil four years ago, there were only 13 penalties in the entire tournament.
There were also two penalties in the game earlier on Monday between Saudi Arabia and Egypt - veteran Egypt goalkeeper Essam Elhadary saved the first before Salman Alfaraj converted the second. Egypt had their entry into the record books too, as goalkeeper Essam El-Hadary became the oldest World Cup player ever, at 45 years and 161 days.More news: FDA approves first cannabis-based drug