South American Zone pacesetters Paraguay suffered a jolt on a seemingly inexorable road to the 2010 FIFA World Cup South Africa™ when they went down 2-0 to Uruguay.
Atletico Madrid's Diego Forlan scored the Uruguayans' opener on 28 minutes, before Diego Lugano made the points safe with a second just before the hour mark in front of 45,000 supporters at the Centenario.
Gerardo Martino's visitors were unable to come back off the ropes as the Paraguayans went down to only their second defeat in 11 games.
With 23 points they still lead Brazil, who have 17 from ten games ahead of tomorrow's meeting with Ecuador in Quito.
Argentina, who the Uruguayans joined on 16 points, will climb second if they beat struggling Venezuela, and close the gap on top spot to four points.
Chile also have 16 points from ten outings ahead of their trip to bottom side Peru. Also tomorrow, Colombia and Bolivia will face off in Bogota, with the hosts hoping for a victory that would keep them in contention.
The top four teams qualify for South Africa 2010, and the fifth-placed team enter a home-and-away play-off with the fourth-placed team from the North, Central America and Caribbean Zone.