“Fervor factor” will be cranked to 11 today in Seattle, D.C.

Major League Soccer will suffer no shortage of atmosphere at the grounds today during the pair of conference final second legs.

According to The Washington Post, officials at RFK Stadium have only a few seats remaining to fill the downsized capacity of 19,647 – which means the lower bowl will be stocking stuffed and on full hop. They will open those upper decks for the title match if United wins, which would mean room for about 45,000. It would be the third time RFK has hosted an MLS Cup, the most recent coming in 2007.

Untied wasn’t part of that one, but certainly was involved in 1997, when more than 57,000 made the cold and rainy scene as United defeated Colorado. Why would so many endure the conditions for the title of a two-year-old league? Post writer Steven Goff explores that very question in a good piece on the club’s special relationship with its fans.

For sure, the faithful from La Barra Brava, the Screaming Eagles, La Norte and the District Ultras will have the place jumping for Sunday’s 4 p.m. ET kickoff.

(MORE: ProSoccerTalk’s Eastern Conference match preview)

Not that the night’s second match will suffer by comparison. CenturyLink Field on the edge of Seattle’s downtown scene long ago became the league’s attendance standard bearer. The Sounders’ average attendance this year, 43,144, set a league record for the fourth year running.  Here’s a little more perspective on those showy figures.

The point here is that there is absolutely no reason to see a drop-off today. In fact, Sounders fans seem to be rallying around the valiant, difficult fight ahead against the Galaxy. With over 43,000 seats already sold, Seattle will establish a new playoff attendance record today.

No question that rave green and just plain raving will be the order of the day downtown in Seattle.

(MORE: ProSoccerTalk’s Western Conference match preview)