Substitute Gonçalo Ramos headed home a Rafael Leão cross deep into stoppage time to send Portugal through to the World Cup last 16 with a dramatic 2-1 victory over Croatia in Toronto.
The result ends Croatia's tournament and likely closes the international chapter of Luka Modrić, while 41-year-old Cristiano Ronaldo rolls on, having scored his first-ever World Cup knockout goal from the penalty spot to draw Portugal level.
A cagey first half produced few clear openings, though Rúben Dias picked up an early booking in the 17th minute that forced Portugal's defence to tread carefully for the remainder of the contest.
Croatia broke the deadlock eight minutes into the second half when Josip Stanišić delivered a cross from the right and Ivan Perišić finished clinically at the back post to give Zlatko Dalić's side the lead.
Portugal responded with fury. Rafael Leão crashed a long-range strike against the crossbar on 57 minutes, and moments later Ronaldo thought he had equalised only for the flag to cut short his celebration for a marginal offside.
Croatia had their own goal chalked off in the same breathless passage of play, with Igor Matanović's effort disallowed because Nikola Vlašić was offside in the buildup.
Roberto Martínez rolled the dice on 62 minutes with a bold quadruple substitution, introducing Bernardo Silva, Francisco Conceição, Gonçalo Ramos, and Nélson Semedo. The gamble would prove inspired.
Four minutes later, VAR awarded Portugal a penalty after Vlašić was adjudged to have fouled Renato Veiga in the box during a corner. Ronaldo stepped up and hammered the ball down the middle to make it 1-1.
That strike made the 41-year-old the oldest player ever to feature in a World Cup knockout match, adding yet another record to an extraordinary career.
Croatia thought they had retaken the lead on 80 minutes through Luka Sučić, but once again the offside flag intervened. Ronaldo departed to a standing ovation moments later, replaced by Rúben Neves.
Then came the decisive moment. In the fourth minute of added time, Leão swung in a cross from the left and Ramos rose highest to power a header beyond the Croatian goalkeeper and send Portugal into raptures.
There was still time for more agony. In the 12th minute of stoppage time, Joško Gvardiol headed home what Croatia believed was a stunning equaliser, but a lengthy VAR review ruled it out for offside.
Frustrated Croatian fans hurled debris onto the pitch as the final whistle confirmed their elimination.
Portugal now advance to face Spain in the last 16 on July 6 in Dallas, while Croatia bow out of what was billed as the last World Cup dance between two of the game's greatest ever players.
