Carlos Tevez missed a first-half penalty as Argentina slumped to a 2-0 defeat away to Ecuador in their World Cup qualifier on Wednesday.
Left-back Walter Ayovi, with a superb strike, and Pablo Palacios scored in the last 20 minutes to hand Argentina their second defeat in four World Cup qualifiers under Diego Maradona.
Lionel Messi also squandered a superb early chance for Argentina, who at least improved on their 6-1 defeat to Bolivia in another high altitude match in April.
Despite the result at 2,800 metres above sea level, Argentina remained in the top four of the 10-team South American group with 22 points from 14 games. But Ecuador closed the gap as they jumped to 20 points.
The top four in the 10-team group qualify directly for South Africa and the fifth plays off over two legs against the fourth team from CONCACAF.