In the energy-sapping thin air of Quito, the Argentines, with World Player of the Year Lionel Messi only playing for the last half hour, had their lead in the South American group cut to three points with Colombia's 2-0 home win over Peru.
Argentina have 26 points, Colombia 23 and Ecuador, who dropped their first points in seven home qualifiers at the Atahualpa where visiting teams struggle at 2,800 metres, remain third with 21.
Argentina made a quick start and Ecuador goalkeeper Alexander Dominguez could only parry Angel di Maria's stinging shot then upended Rodrigo Palacio as the striker chased the loose ball.
"We've been making do with draws," Messi, who recently recovered from a hamstring injury, complained after Argentina's third successive stalemate result in the qualifiers. "We are closer to qualifying and that's what's important."
"We scored a quick goal and I wonder if the goalkeeper shouldn't have been sent off.
"It's difficult to play here, then they equalised," added Messi, who had also struggled in the rarefied air in La Paz, which is even higher than Quito, in the 1-1 draw with Bolivia in March.
The top four teams at the end of the qualifiers in October will go through to next year's finals in Brazil.
