Pato made an early foray but failed to bring the ball under control, then had a header easily claimed by Venezuela keeper Renny Vega before the latter held a shot from the AC Milan forward at the second attempt.
Pato then hit the bar as Brazil continued to be frustrated. Venezuela were not to be outdone and the impressive Tomas Rincon was held up in his tracks when he was set for a clean run on goal as Bolivian referee Raul Orozco elected to stop play for a foul by Thiago Silva ten minutes before the break.
Brazil then were unlucky as Neymar fed Robinho but Oswaldo Vizcarrondo made a last ditch block almost on the line. Then Ganso founde Neymar but he missed the target
The Brazilians have their eye firmly on the 2014 World Cup which they will host - yet they are also after their ninth Copa and fifth in the past six editions.
They first won the regional championship in 1919, adding further triumphs in 1922, 1949, 1989, 1997, 1999, 2004 and 2007. Argentina and Uruguay hold the record with 14 each.
The favourites continued to press after the break - but had a scare on 59 minutes when Salmon Rondon went down after tangling with Silva in the box. But Orozco booked Rondon for simulation.
Menezes rolled the dice on the hour, withdrawing Robinho and sending on Fluminense's Fred. Yet it was Venezuela who came close next as Juan Arango dragged an effort wide
Elano and Lucas Silva came on for the tiring Pato and Ramires with 15 minutes remaining but the resolute Venezuelan defence, in which Roberto Rosales and Vizcarrondo were outstanding, held firm.
PTI