Boca’s Sebastian Villa came from Colombia closest to breaking the stoppage in the first half but hit the woodwork.
The winners who come after the second leg next week in Brazil will face either Brazilian Palmeiras or arch-rivals Boca River Plate in the January 30 final at the Maracana stadium in Rio de Janeiro.
Palmeiras stunned the 2018 River 3-0 winners Buenos Aires Tuesday.
There were high chances in the Bombonera that there were no observers due to coronavirus restrictions.
Villa broke an early opportunity from the woodwork after being slammed by former Manchester United, Manchester City and Juventus former Carlos Tevez.
Six-time winner Boca threatened early in the second period when Eduardo Salvio’s Santos goalkeeper John Victor was pushed close to a post.
Just after the hour mark, Santos were under a lot of pressure but Marinho’s low shot was saved by the keeper. Esteban Andrada before Kaio Jorge shook over the bar.
With 15 minutes left it looked like Marinho was clearly fouled in the box by Carlos Izquierdoz but surprisingly, despite the assistant video referee investigating what happened, the referee dismissed appeals. peanas Santos.
Tevez blocked a wide attempt after he cut in from the left while deep into injury time Leonardo Jara it was built on the edge of the area but thwarted his effort when Boca finished strong.
Boca last won the Libertadores in 2007 but lost to River in the big 2019 final that needs to be played in Madrid after deactivating the first second leg when River fans attacked Boca’s team bus on the way to the stadium.
Three Santos time winners, the team known as the great Pele Pele, lifted the final trophy in 2011.