Real Salt Lake put off writing that next chapter in their "Big Book of Almosts" midweek, eking out a 2-1 aggregate win over the LA Galaxy.

Beating the two-time defending MLS Cup champions is quite a thing, especially for a group that have a habit of not quite getting over the hump. But right now, beating the Portland Timbers -- undefeated since an August loss to, yes, Real Salt Lake -- might be even tougher.

RSL beat Portland twice at home in three weeks back in August, with a thrilling 3-3 draw at JELD-WEN Field thrown into the mix as well. Their most recent meeting, in the middle of October, produced a much more cautious 0-0 draw.

Here's why, and how that will affect tonight's opener in the Western Conference Championship (9 pm ET; ESPN):

Combine through the middle to create avenues of attack

No team in the league checks to the ball to bring a defender up, then moves into space quite as quickly as the Timbers do. They love small combination play through the middle, and have become something of a juggernaut as Caleb Porter continues to fuse the soccer brains of his core players:

Those are some pretty good defenders -- Osvaldo Alonso was in the middle of that play -- that Portland just carved up.

Also worth noting the role Rodney Wallace played right there, and on Diego Valeri's goal against Seattle in the second leg:

Wallace originally won his starting role for the Timbers because he offered penetration on the left flank. As he's gotten more comfortable his responsibilities have grown, and he understands now that if you come at him, he can put the ball into space for a teammate.

That's the defining principle of how Porter has his team attack. Forget positions, formations or anything else: It's all about getting into space at pace.

We knew Valeri would be excellent at it, and Darlington Nagbe as well, but Wallace's ascent -- first as a goalscorer, but now as a chance creator -- has lifted the Timbers to a higher level. There are just too many options out there for most teams to handle.

One more, for fun:

If RSL are spending a lot of time stopping attacks that look like this, they're going to be in trouble. Chris Schuler and Nat Borchers both did great emergency defensive work against LA, but the Timbers are executing through the middle and into the final third with a ruthlessness and precision that the Galaxy couldn't match.

Make the central defense defend on the back foot

Easier said than done, of course. But it needs to be done by RSL to open up time and space for their attackers -- especially Javier Morales, who has struggled somewhat over the last couple of months.

Robbie Findley has been excellent at this, and changed the shape of the series against LA.

In the first leg, which the Galaxy won 1-0, here are Omar Gonzalez's defensive interventions before Findley came onto the field:

And here's what Gonzalez's night looked like when he had to chase Findley:

RSL can't let Futty Danso and Pa Modou-Kah get that much leeway to step into the middle and block lanes, or -- worse -- physically dominate smaller, quicker attackers. Everything has to be crisp, and diagonal runs have to be happening all the time.

Here, Danso has to come way up the field and to the sideline to track Obafemi Martins, who slips a little pass inside to Eddie Johnson:

Portland's defensive rotation was good, but EJ had to do more there. And Devon Sandoval -- who should get the start in place of the injured Alvaro Saborio -- has to do more Sunday night.

One last little note:

Set pieces. RSL annihiliated the Timbers on restarts back in August, and Seattle scored two of their three goals against Portland last week from long throw-ins. Watch for that Sunday, and in two weeks.