River Plate beat fierce rivals Boca Juniors 2-0 in the first leg of their copa libertadores semi-final.
River Plate went in front this time when Rafael Borre converted a penalty after the referee consulted with VAR.
An Ignacio Fernandez strike in the second half doubled the lead.
Boca midfielder Nicolas Capaldo, who blazed a shot over the bar with just the keeper to beat when his side were 1-0 down, was sent-off in injury-time after another VAR intervention.
The second leg at Boca will take place on 22 October.