There were 24 teams from North and Central America and the Caribbean to start. RSL and Monterrey are the last two standing.
The first leg will be played Wednesday at 8 p.m. MDT and can be seen live on the Fox Soccer Channel and TeleFutura. The second leg is scheduled for April 27 at Rio Tinto Stadium.
"They attack well and have some good strikers," RSL goalkeeper Nick Rimando said. "They're a good team, but we've played some good teams in this competition already so it will be an interesting match because we haven't met each other before.
"It will be a good battle."
Monterrey needed a penalty kick in the 81st minute from Chilean forward Humberto Suazo to edge Cruz Azul 2-1 and win 6-4 on aggregate. Cruz Azul was attempting to gain its third consecutive berth in the CONCACAF Champions League final.
"Their style of play is similar to ours," RSL defender Nat Borchers said. "They're going to match up with our diamond midfield and they're going to match up with us on top as well. It's going to be difficult. They're a very athletic and technically gifted team, so we're going to have to very aware of the counterattack, of their buildup."
For RSL, it will almost be like looking into a mirror. RSL coach Jason Kreis believes that the match will boil down to individual matchups.
As far as the importance of it all, the reality of it has finally struck home. It is a big deal, as RSL has become the talk of MLS.
"It really is [big]," Kreis said. "At the beginning of last year I would have told you that we were really excited about the opportunity, but [I] probably didn't appreciate exactly how important it was or it could be for our club until now. We tried to handle it the best way we could and say we were very serious about it, but now sitting where we're at, I'm really, really appreciative to the guys for what they've put into this to give us this terrific, terrific opportunity."
RSL at Monterrey
P Wednesday, 8 p.m.
TV • Fox Soccer Channel, TeleFutura