CARY - At some point tonight, the Carolina RailHawks will admit their 100,000th fan to SAS Soccer Park, if you include exhibition games and cup competitions. That's not bad, considering they drew zero last season.

It's been an up-and-down season for the first-year pro soccer team, but it's finishing on an up. The RailHawks, after clinching the eighth and final United Soccer Leagues First Division playoff spot in their final game of the season, open the postseason tonight at home against the first- place Seattle Sounders.

This after an improbable, remarkable run through the U.S. Open Cup that went largely under the radar in the Triangle before the RailHawks lost to an MLS team in the semifinals -- in overtime, no less.

And they finished fifth out of 12 USL teams in attendance, averaging 5,124 fans per game, about 70 percent of capacity. For most expansion teams, that would be more than enough for their first season. The RailHawks set the bar a little higher.

"Especially at the beginning with a lot of the ties and when we went on a streak of not winning, we still had a couple thousand fans out there," Carolina midfielder and former UNC star Chris Carrieri said. "It's pretty tremendous. I loved it. It was awesome. I'm proud to get in there [tonight] and see if we can pack the place. It's well beyond what I expected."

RailHawks managing partner Chris Economides said, "I don't like to use the 'expansion excuse' as an excuse. We've met our expectations so far."

There's a reason the Sounders won the regular-season title. They're deep and strong. Like Carolina, they made it to the semis of the Open Cup. Sunday night's second leg of the two-game playoff will be played at Qwest Field, which the Sounders share with the Seattle Seahawks. You could fit all of SAS Soccer Park inside.

But the RailHawks don't have any intention of going quietly. And given that they already have rallied from the kind of struggles that would sink most expansion teams, it's hard to count them out.

"Usually when you have a team that goes through spurts like we went through, you say, 'It's not our year,' " said former N.C. State star Scott Schweitzer, the team's 37-year-old rookie coach. "They never said that. They said, 'We'll do what we need to do, we'll get into the playoffs, and once we get there we'll make it our year.' "

The RailHawks lost all four of their preseason games and went 0-1-3 to open the season, then struggled through a July that saw them play nine games in 28 days. They won only one, but it was a big one -- over MLS' Chicago Fire in an Open Cup game.

That probably could have been it. But the RailHawks rallied in August and came into the final week of the season with a cross-country road trip and everything on the line. After facing the New England Revolution in the Open Cup semifinals, they had to win one of their final two games to make the USL playoffs.

The game against the Revolution was just short of bloody. After Carolina took an early 1-0 lead, two players were ejected in the first half, one from each team, and the RailHawks had another sent off in the second after New England equalized.

Down to nine men, they held off the Revs until giving up the winner in overtime. The bus left at 2:45 a.m. the next morning and broke down on the way to the airport. The RailHawks lost 5-0 at the Minnesota Thunder, leaving their season hanging in the balance.

But they went to San Francisco two days later and beat California, another expansion team with a less-certain future, to set up this weekend's playoff series.

The RailHawks are molded in Schweitzer's image, rough and defensive-minded. He never was known for going in easy on a tackle, and four RailHawks players are among the USL First Division's top 11 in fouls. They went 8-12-8 in the regular season, but had 12 shutouts.

"What we've gone through this year wasn't great, but we're in the playoffs," Carrieri said. "A first-year team, we're in the playoffs, and anything can happen."

They may not beat Seattle this weekend. But they certainly won't make it easy on the Sounders.

That's kind of the way their season has gone. They haven't made it easy. But so far, they've made it.