Enner Valencia scored his third goal of the World Cup before being taken off on a stretcher as Ecuador drew with the Netherlands to leave Group A wide open.
PSV Eindhoven forward Cody Gakpo had given the Netherlands the lead after just five minutes and four seconds - the quickest goal so far in Qatar - when he struck a shot beautifully into the top of the net.
But the Dutch struggled to build on their lead, with Ecuador's Pervis Estupinan having a goal disallowed on the stroke of half-time.
Ecuador fans were bouncing with excitement throughout the second half at the Khalifa International Stadium as they equalised just after the break and continued to create chances against a rattled Netherlands side.
The entire Ecuador squad ran over to the corner flag to celebrate with Valencia after he poked in the rebound from Estupinan's parried shot in the 49th minute - and Gonzalo Plata hit the crossbar with a long-range effort shortly after.
Captain Valencia, who scored both goals in Ecuador's victory over hosts Qatar on the opening night of the World Cup, was a constant threat but his night was cut short due to injury.
The former West Ham and Everton striker went down in the final minute of normal time and was taken off on a stretcher, but was seen hobbling to his seat in the dugout.
The result means three teams from Group A will be battling it out for a place in the last 16 in the final group match - the Netherlands, Ecuador and Senegal - with all three capable of going through as table leaders.
With the Netherlands heavy favourites going into their final group game against bottom side Qatar, all eyes will be on a showdown between Ecuador and Senegal, which will dictate the table order.
Gakpo's opener was the first goal Ecuador had conceded in 701 minutes across all competitions - and a first since March - but the Netherlands struggled to create much as the game wore on.
Estupinan was left frustrated at half-time, with several of his team-mates remaining on the pitch to chat to the officials after his goal was ruled out when team-mate Jackson Porozo was offside and obstructing the view of the goalkeeper.
Netherlands boss Louis van Gaal brought on Memphis Depay at half-time - a planned move as the Barcelona forward continues his return to fitness following injury - but it made little difference as Ecuador were unlucky not to pick up all three points.
