Spain laboured to an uninspiring 1-0 victory over Iberian rivals Portugal in their last-16 tie to set up a quarter-final meeting with resurgent Belgium.
In an underwhelming game that failed to live up to billing in Dallas, Mikel Merino proved decisive, arriving late from the bench and latching onto a smart Ferran Torres pass to plant beyond the clutches of Diogo Costa in second-half stoppage time.
His calm and conclusive strike was the only real moment of quality from an encounter boasting so many superstars, none of whom were able to rise to the occasion quite in the way many rival nations' high-profile players have.
The result, of course, had consequences for Portugal beyond ending their tournament. Roberto Martinez stepped down as head coach, while Cristiano Ronaldo revealed before the game that this summer would mark his last appearance at a World Cup.
The Portugal captain was visibly emotional at the close, knowing his side failed to properly show up for his final farewell tour on the world stage. There will be no fairytale ending to an international career that spectacularly spanned two decades.
Ronaldo was actually the only Portugal player to land a shot on target all night, with Spain's immense control and impressive defensive structure winning out. They have become the first team in World Cup history to register six successive clean sheets, and are yet to concede a goal at this tournament.
Luis de la Fuente's side advance to the quarter-final stage for the first time since winning their only World Cup title back in 2010 in South Africa, and face a revived Belgium side on Friday after they .
3: SAVE! Mikel Oyarzabal draws a decent stop from Diogo Costa by landing the first effort on target of the game.
8: SITTER! Oyarzabal dragged his effort wide from a promising position in acres of space.
11: VAR! Ronaldo claims for a penalty after a scuffle with Rodri in the box, where he ends up floored. VAR check but nothing given.
16: DOUBLE SAVE! Diogo Costa produces two stops to deny both Lamine Yamal and Baena on the follow-up.
37: CHANCE! Ronaldo latches onto a glancing header across goal from Joao Felix but can't beat Unai Simon.
41: Nuno Mendes rattles a rasping effort off the crossbar via the head of Pedro Porro.
76: MISS! Bruno Fernandes crashes an effort into the side-netting after good work from substitute Rafael Leao.
90+1: GOAL! Merino is slipped through by Torres and beats Costa with a neat, low finish inside the post.
Cristiano Ronaldo's 27th World Cup appearance conspired to be his last. He scored in all six editions in which he appeared, holding the all-time record for highest number of tournaments scored at.
Your Site pundit Chris Sutton blasted both Ronaldo and Martinez for Portugal's World Cup exit - adding that the now-former boss also made a mess of Belgium.
Speaking on BBC Radio 5 Live, he said: "He [Ronaldo] is waddling around the field like a grandad, that's why Portugal are out. Ronaldo does nothing: he did nothing. What is Roberto Martinez doing? How can you pander to a player so much? Portugal are out because of Roberto Martinez.
It's scandalous the way he has managed this team. He made a mess of Belgium when they had an opportunity of really doing great things with that golden generation; they ended up Belgian buffoons. Now Portugal, it was pathetic to see a manager act in that manner."
Analysis by Your Site' Laura Hunter:
For two nations steeped in neighbourly tension and bursting with endless talent, this contest failed to deliver on many levels. The expectation was through the roof but what actually transpired was a cagey affair between two sides lacking spark.
The big hitters were largely anonymous. There was none of the old foe feel, added spice, or sense of occasion you would associate with his type of rivalry.
Merino's composed finish in stoppage time was at least respite from the underwhelming back and forth of the regulation 90 minutes - not the first time the Arsenal forward has come up clutch to settle a big game.
In Portugal the inquest will begin: Was Ronaldo the right man to lead this young, vibrant and exciting ensemble of Portuguese players? Was their campaign sacrificed to give their ageing talisman his last hurrah? Perhaps.
The stoic look on his face and brief acknowledging wave to fans showed this was not the desired end, and yet, for most other observers, it always felt like the most probable.
Roberto Martinez speaking after defeat to Spain:
"I came to Portugal to win the World Cup and I think that, without winning it, there's no point in continuing.
"The board and the president now have the opportunity to choose the new manager... my contract ends today. There isn't much more to say.
"Yes, it's my last game for the national team. I'm very proud. I've felt welcomed as just another Portuguese person, in a very warm way. It's been a pleasure, a source of pride and a responsibility."
