RSL took out the first leg 2-0 at home on March 16 and will now strive to maintain that advantage in San Jose for the chance to join the already-qualified clubs in North and Central America and Caribbean's premier club competition.
A last-start MLs win over LA Galaxy, who have already qualified for the Champions League, has given RSL plenty of confidence according to veteran defender Nat Borchers.
"I think we're feeling confident," Borchers told MLSsoccer.com. "Given our result against LA, that gave us a big boost to win big against them.
"[Saprissa] are going to come at us early and managing the game is going to be the biggest factor for us. It's going to be crucial to make sure we're not giving anything up in the first 15 to 20 minutes."
RSL has been given plenty of support from around the league and will be hoping to do MLS proud by getting the right result at the Estadio Ricardo Saprissa Ayma.