american futbolPORTLAND, Ore. — With fans boisterously embracing the potential rivalry, Major League Soccer’s Seattle Sounders beat the Portland Timbers of the USL’s First Division 2-1 on Wednesday night in the third round of the Lamar Hunt U.S. Open Cup. It was the first official meeting between the clubs since the Sounders joined MLS this season. Portland has been awarded an MLS franchise to start play in 2011.

The game was a sellout, with Sounders fans traveling south en masse and trading chants with Portland’s equally enthusiastic supporters. A few Timbers fans displayed a sign reading “A league below, a class above.”

The Timbers play a step down from the MLS in the United Soccer Leagues’ top division.

The U.S. Open Cup is an annual competition open to all amateur and professional soccer teams affiliated with U.S. Soccer. The tournament dates to 1914.

Seattle silenced the home crowd early when Roger Levesque scored 49 seconds into the game. Stephen King’s goal at exactly the 27th-minute mark made it 2-0.

Portland’s Mandjou Keita beat Kasey Keller inside the far post in the 43rd minute.

The first two rounds feature teams from amateur and lower-rung professional leagues. MLS teams join the competition in the third round.

The Sounders are 9-7-3 overall and 6-3-7 in MLS play this season. They will play the Kansas City Wizards in the quarterfinals of the U.S. Open Cup.

The Timbers, who are 10-2-5 overall, had not lost in 15 straight games.

The game, attended by 16,382, was the first sellout in modern Timbers’ history. It was such a draw that fans watched from outside the fence overlooking the field on 18th Avenue.

“This is going to be a hot bed of soccer in the nation,” Keller predicted. “I think it’s going to be a catalyst for the MLS.”

Portland and Seattle have enjoyed a soccer rivalry dating to 1975 when the two sides were members of the North American Soccer League. The Timbers were 11-16-5 against the Sounders from 2001-08 as rivals in the USL First Division.

The rivalry has taken on greater significance now that Portland is set to join the MLS — along with a franchise to the north in Vancouver — bringing the league to 18 teams.

The Timbers, owned by Merritt Paulson, will keep their name and their colors when they make the leap. Their home, PGE Park, must be remodeled to meet MLS specifications.

The Triple-A Portland Beavers baseball team, who are also owned by Paulson and play at PGE Park, will have to find a new home. Two proposals — one of which would have put a new Beavers’ stadium adjacent to the Rose Garden where the NBA’s Trail Blazers play — have been shot down.

City officials who have signed off on the MLS deal are still discussing how to fund Portland’s portion of the costs involved.

Paulson, the son of former Treasury Secretary Henry Paulson, must have a signed financing deal with the city to renovate PGE Park by Sept. 1 to secure the MLS franchise.

“It was tremendously exciting,” Paulson said about the response to the game. “It’s just a little sliver of what the MLS can be here in Portland.”