Gremio suffered a 2-1 loss to Chilean outfit Huachipato in Porto Alegre as they made a slow start in Group 8 of the Copa Libertadores.
Federico Falcone opened the scoring from close range after a Braian Rodriguez cutback to give the visitors a 17th-minute lead on Thursday.
Rodriguez went from provider to scorer six minutes into the second half as he powered a header into the bottom corner after Jose Contreras' cross.
Two-time champions Gremio pulled a goal back through Hernan Barcos' penalty, but Huachipato held on for an important away win.
Argentine outfit Newell's Old Boys proved too good for Paraguay's Olimpia, winning 3-1 at home in their Group 7 clash.
An Ignacio Scocco penalty and Horacio Orzan tap-in saw the hosts to a 2-0 lead before Olimpia pulled one back through Fredy Bareiro.
But the result was sealed late on thanks to former Liverpool midfielder Maxi Rodriguez, who struck at the back post.
A 68th-minute goal from Patrick Vieira saw Palmeiras to a 2-1 win at home to Peruvian side Sporting Cristal.
Carlos Lobaton cancelled out Henrique's opener with a 52nd-minute penalty before Vieira scored the winner.
Bolivia's The Strongest recorded a 2-1 victory over Argentine outfit Arsenal in La Paz.
A long-range Alejandro Chumacero strike was cancelled out by Dario Benedetto's 49th-minute free-kick.
Arsenal were reduced to nine men as Damian Perez and Emilio Zelaya were sent off and The Strongest took advantage as Luis Melgar scored the winner six minutes from time.
In Group 6, Deportes Tolima registered a 2-1 victory against Cerro Porteno at the Estadio Manuel Murillo Toro.
A Luis Cardozo own goal and David Silva effort put the Colombians on track and they held on despite Williams Martinez pulling one back for the visiting Paraguayans.