A strangely subdued Qwest Field soccer crowd watched the Seattle Sounders FC walk off the field Thursday night for what could be the last time in 2009.

It was as if the fans didn’t know whether to cheer the shutout effort of the home team, or bemoan its failure to score against the visiting Houston Dynamo, or scream at the referees for disallowing an apparent Nate Jaqua goal that would’ve given Seattle a 1-0 victory.

Adding to the uncertainty was the possibility that the Sounders could be eliminated on Nov. 8, when they face the Dynamo at Houston in what will amount to the “second half” of a 180-minute playoff contest decided over 11 days in two cities.

An expansion season that has exceeded the expectations of even the most fervent pro-soccer optimists in the Pacific Northwest deserves closure – the same kind of goodbye the Mariners shared with their fans at Safeco Field a few weeks ago.

But how do you close what’s very much open? If the Sounders travel to Houston and prevail by a goal in regulation time on Nov. 8, they could return to Qwest Field for a second-round playoff game against Chivas USA. Or they could be required to go to Los Angeles in the second round to face the Galaxy.

On the other hand, the Sounders could be extended into another 90-minute draw at Houston, in which case they’d be challenged to settle the issue either in a 30-minute overtime, or with penalty kicks.

Finally, there’s this to consider: Even if a victory at Houston puts the Sounders on the road against the Galaxy in the second round, they could make a scintillating return to Qwest Field for the MLS Cup on Nov. 22.

That’s a lot of scenarios for the crowd to ponder. No wonder there wasn’t a prevailing emotion Thursday night.

“You always want to win at home,” said coach Sigi Schmid. “But we don’t look at it as a lost opportunity. We look at it as, ‘Hey, we played the first half of the series and we didn’t get a goal.’ Now we just have to make sure we get the goals in the second half of the series.”

If Sounders fans are familiar with anything, it’s a game without the home team scoring. Between Seattle’s 2-1 victory over Houston on July 11, and its 2-1 victory over FC Dallas last Saturday, Qwest Field crowds watched 466 minutes of action – slightly more than five games – between home goals.

And yet, the absence of offensive fireworks did not discourage fans from turning out.

After setting an MLS attendance record during the regular season – they averaged 30,897 – Seattle’s crowd of 35,807 on Thursday set another MLS record: largest crowd for a conference semifinal game. (It also was the seventh largest for any MLS playoff game.)

But the homefield edge never asserted itself against the Dynamo, two-time league champions (2006-07) who, because of their recent participation in the CONCACAF Cup, were playing their fourth game in 10 days.

“They’ve been the dominant team in the Western Conference the last three, four years – or even further, if you count their days in San Jose,” said Schmid. “And we’re the new kids on the block, trying to get people to take notice of us. They don’t want to give away any of their prestige, and we’re trying to take some of it. It makes for a good rivalry.”

So do some edgy tempers. In the 16th minute, Houston goalkeeper Pat Onstad nearly came to blows with Sounders forward Fredy Montero, whose mood wasn’t helped by a recent case of the flu. Both were issued yellow cards.

Whenever he touched the ball after the incident, Onstad was loudly jeered.

But the 41-year old Vancouver, B.C., native is beyond allowing a crowd to unravel him.

Onstad was responsible for strong saves on a Steve Zakuani breakaway and a Patrick Ianni header. Another Ianni attempt, on a header off a first-half corner kick, was stopped by midfielder Brian Mullan.

Otherwise, there weren’t many other scoring opportunities for either team. The best way to describe Thursday night’s sort-of, maybe, not-quite but possibly could be season finale?

“To Be Continued …”

“We want to give our fans an opportunity to come out again,” said Schmid. “That means we’ve got to go down to Houston and win.”