(CNN) -- Diego Maradona's Argentina suffered a potentially fatal blow to their World Cup qualification hopes after a 1-0 defeat against Paraguay in Asuncion.
Argentina coach Diego Maradona faces an uncertain future as his side struggle to qualify for South Africa.
A 28th-minute strike by Nelson Haedo Valdez saw the Guaranies advance to their fourth World Cup in a row.
However there was further misery for Argentina in the second half when Juan Sebastian Veron was sent off.
Maradona, who is under intense pressure after a poor campaign, remained defiant in defeat.
Blog: Why Argentina will still qualify.
"It is down to poor form and failures as a team," he was quoted by FIFA.com as saying. "We must re-start and do the puzzle again. I didn't think we were going to be like we are. I wanted to be higher in the table.
"I am not afraid of criticism. I am afraid of nobody. I am doing my job, I have my team and I am going to go forward," he added.
"I have been battling critics since I was 15 years old. Now I am 48 and I am going to continue to battle with them [the press]."
The result leaves his star-studded side in fifth spot in the highly-competitive South American qualifying group behind Ecuador, who kept their own campaign on track with a 3-1 victory over Bolivia in the high-altitude surroundings of La Paz.
The top four teams automatically qualify for the finals in South Africa, with the fifth facing a play-off against the fourth-placed team from the tightly-contested CONCACAF group -- which was Costa Rica after Wednesday's matches.
Nilmar netted a hat-trick to lead Brazil to a ninth victory in the campaign.
Paraguay are three points back in second, while Chile remained third on 27 --- four clear of Ecuador and five ahead of Argentina.
Many teams have struggled when playing 3,600 metres above sea level at the home ground of Bolivia -- notably Argentina who were defeated 6-1 there in the previous round of qualifiers -- but Ecuador acclimatized well.
It took only four minutes for Edison Mendez to open the scoring for the travelers before Luis Valencia finished a crisp counter attack to double the lead just after the start of the second half.
Cristian Benitez, who joined English side Birmingham City recently, made it three-nil 10 minutes later, completing a good reaction from Sixto Vizuete's side after their defeat to Colombia at the weekend.
With only five minutes left of the game Gerardo Yecerotte netted for the home side for a consolation goal; elimination had already been confirmed with previous results.
In Montevideo, Uruguay kept their qualification hopes alive after goals from Luis Suarez, Andres Scotti and Sebastian Eguren gave them a 3-1 win over Colombia to be on 21 points above Venezuela on goal difference.
Peru are bottom with just 10 points, two adrift of Colombia.
In the remaining fixtures, Argentina host Peru on October 10 and then travel to Uruguay three days later for a match which should decide who goes into the two-leg play-off.
Uruguay's other game is away to Ecuador, who close their campaign away to Chile.
Chile will hope to have sealed qualification before then with victory in their October 10 trip to Colombia, whose last match is away to Paraguay.
Venezuela face a difficult task to claim fifth place, with a home clash with Paraguay and then a trip to Brazil.