In a rematch of last year's final, two-time champions Monterrey escaped with the draw despite playing with 10 men for much of the second half after Cesar Delgado was sent off for a late challenge in the 66th minute.
Santos' Carlos Darwin Quintero had a great chance in the dying minutes but his shot from inside the six-yard box was blocked by Darvin Chavez.
The second leg is scheduled for May 1 at the Estadio Tecnologico in Monterrey. The confederation's champion advances to the FIFA Club World Cup in Morocco in December.
Monterrey prevailed in last year's final, beating Santos 3-2 on aggregate.