Local giants Boca Juniors and Santos of Brazil played out a tense 0-0 draw at an empty Bombonera stadium in Buenos Aires on Wednesday in their Copa Libertadores semi-final first leg tie.
Boca's Colombian forward Sebastián Villa came closest to breaking the deadlock in the first half but struck the woodwork.
The winners following next week's second leg in Brazil will face either Brazilians Palmeiras or Boca's arch city rivals River Plate in the January 30 final at Rio de Janeiro's Maracanã stadium.
Palmeiras stunned 2018 winners River 3-0 in Buenos Aires on Tuesday.
Chances were at a premium in the Bombonera that was devoid of spectators due to coronavirus restrictions.
Villa crashed an early chance off the woodwork after he was teed up by veteran former Manchester United, Manchester City and Juventus star Carlos Tevez.
Six-time winners Boca threatened early in the second period when Eduardo Salvio's near post shot was pushed behind by Santos goalkeeper John Victor.
Just after the hour mark, Santos enjoyed a spell of pressure but Marinho's low shot was saved by goalkeeper Esteban Andrada before Kaio Jorge blazed over the bar.
With 15 minutes left Marinho appeared to be clearly fouled in the box by Carlos Izquierdoz but incredibly, despite the video assistant referee checking the incident, the referee waved away Santos' penalty appeals.
Tevez curled an effort wide after cutting in from the left while deep into injury time Leonardo Jara was teed up on the edge of the area but lashed his effort well over as Boca finished strongly.
Boca last won the Libertadores in 2007 but lost to River in the epic 2019 final that had to be played in Madrid after the original second leg was postponed when Boca's team bus was attacked by River fans on the way to the stadium.
Three time champions Santos, the team Brazil great Pele played for, last lifted the trophy in 2011.