RIO DE JANEIRO, Feb 16 (Reuters) - Former champions Gremio beat Cerro Porteno of Paraguay 1-0 away in an ugly Libertadores Cup match marred by crowd trouble, provocation and play-acting on Thursday.
Gremio's fellow Brazilians Parana also won away from home, beating UA Maracaibo 4-2 in a more tranquil match in Venezuela.
Gremio's Group Three game in Asuncion was held up for three minutes in the first half as rival fans pelted each other with plastic seats and lumps of concrete before riot police calmed the situation.
There was more trouble as the teams returned for the second half as pieces of concrete were thrown at the Gremio bench.
Late in the game, Gremio midfielder Lucas was hit by a bottle thrown from the crowd who became incensed at what they saw as blatant play-acting and time-wasting by the visitors as they defended their 1-0 lead.
Lucas scored Gremio's winner in the 53rd minute, meeting a poor clearance with a full-blooded first time drive from the edge of the penalty area.
But there was a dramatic finale as Cerro Porteno striker Cesar Ramirez had a penalty superbly saved in the 89th minute by Gremio goalkeeper Sebastian Saja.
That led to a shoving match between the players in the penalty area and more bottle-throwing by the home fans.
At the end of the game, referee Hector Baldassi was surrounded by angry Cerro Porteno players and coach Gustavo Costas.
Argentine keeper Saja was Gremio's hero as he made superb saves to defy Lorgio Alvarez and Gustavo Morinigo in the first half and Ramirez and Jorge Nunes in the second before capping his evening with the penalty save.
UA Maracaibo and Parana went in 1-1 at halftime as Josiel fired the visitors ahead in the 39th minute and Daniel Arismendi levelled for the Venezuelans one minute before the break in Group Five.
Dinelson and Henrique scored twice in two minutes to put Parana in command and, although Cristian Casseres pulled one back for Maracaibo in the 67th minute, Gerson restored Parana's two-goal advantage in the next attack.
Parana went top of the group with three points, ahead of compatriots Flamengo and Bolivia's Real Potosi who have one each.