For a team with its back to wall, a tremendous season at stake in the team’s first postseason series, Sporting Kansas City showed no hint of jitters Tuesday during training at the club’s Swope Park facility.

Quite the contrary, players laughed and prodded the team’s backup goalkeepers during penalty kick practice — just in case the Eastern Conference semifinals are decided in a shootout at 8 p.m. tonight at Livestrong Sporting Park.

Sporting KC’s players even huddled with Sporting Club’s sales team, which showed up en masse to watch what might be the final training session of the season barring a substantial result.

Trailing 2-0 halfway through the two-game aggregate series against the Houston Dynamo after a lethargic performance Sunday, Sporting KC needs to win by at least two goals in regulation to keep alive its MLS Cup title dreams.

Of course, it all starts with “the next 45 minutes.”

That’s been manager Peter Vermes’ mantra all season.

Repeatedly, in news conferences and with his team, he stressed the importance of the next 45 minutes — how that was all that was laid out before Sporting KC, all that mattered and all the squad should be focused on.

And it worked too.

Sporting KC repeated as regular-season conference champions for the first time in club history and won the Lamar Hunt U.S. Open Cup for the second time as well.

Now, of course, needing to erase that two-goal hole, Sporting KC is set to play the most important 45 minutes of its season.

“This is the only game we’ve got to look forward to right now,” said midfielder Roger Espinoza, who played 77 minutes in the opening leg after missing a month with a sprained ankle. “This is it right here – the most important 45 minutes — but this is what we play for, to make amazing things happen.”

Amazing? Yes. Unprecedented? No.

Nearly every year, one or more teams overcome a first-leg deficit to march on in the MLS playoffs. Sporting KC hopes that — just as in 2004 — it’s their turn to do the improbable.

“Every guy in the locker room, we all believe that we’re going to make history,” center back Matt Besler said. “There’s not one guy who thinks our season is going to end (today).”

Forward Kei Kamara popped in a video of the then-Wizards’ 4-3 win Sept. 22, 2010, against Houston for inspiration and proof of what’s possible. The club trailed 3-1 that night at CommunityAmerica Ballpark before rallying.

“We have a lot of confidence,” Espinoza said. “It’s happened before. If it was something that had never happened in soccer before in the world, maybe we’d be scared. But it’s been done before in the history of soccer and teams have come back from worse. It’s been done in Kansas City; this team has done it.”

If Sporting KC is going to get it done, though, it will do so with a depleted midfield.

Midfielder Paulo Nagamura is “not ready yet,” Vermes said. “He’s still got some pain. He’s jogging, but he’s not ready yet.”

Defensive midfielder Julio Cesar also is likely to be out after straining a quad late in Sunday’s first leg.

Of course, Vermes won’t stand for excuses. The game is going to be played with whomever is available and Houston won’t feel sorry for Sporting KC.

The bottom line is that Sporting KC needs a goal — and the sooner the better to put the issue back in doubt.

“The first goal is everything,” Besler said. “We can get the second one until we get the first one. That’s all we’re worried about right now is getting that first one. Once we do, we really feel like the tides will turn in our favor and we’ll have the momentum. Then, hopefully we’ll get that second.”

Count captain and goalkeeper Jimmy Nielsen among those who feels like that goal will be coming.

“I think tomorrow night you’ll see me with a big cigar,” Nielsen said. “That’s my prediction. I have a very good feeling about tomorrow. And why do I have that feeling? We’ve played Houston a lot of times with no success … but the atmosphere and the way we’ve been looking at each other gives me big confidence.”

Fan behavior receives attention

The Houston Chronicle’s Soccer y Futbol blog lobbed accusations of fan misconduct at Sporting Kansas City supporters, who are alleged to have asked to see the green cards of Houston Dynamo supporters during the 2011 Eastern Conference final.

Major League Soccer said in a release that it “conducted a thorough investigation into this accusation in 2011,” but the league found no grounds for action against Sporting KC or its supporters’ group, The Cauldron.

That investigation concluded that “at no time during or after the event during or after the event was the stadium, home club, traveling liaison or MLS made aware of comments that would be deemed racist in nature.”

However, it is an issue the league is aware of and works to combat.

“Allegations of this nature are taken seriously by Major League Soccer,” MLS Executive Vice President Dan Courtemanche said a statement. “We have no tolerance for discriminatory or racist language and behavior from anyone participating in or attending our events.”

Violators face a lifetime ban and possible criminal investigation.

By contrast, Dynamo supporters did lose privileges after smoke bombs were thrown onto the field at Livestrong Sporting Park after that same game.

League-wide, sanctioned supporters groups are allowed to bring in flags, banners and musical instruments among other approved items that most fans are prohibited from bringing into the stadium.

After repeated problems with Dynamo supporters groups, including additional incidents with incendiary devices or other objects being throwing onto the field, MLS temporarily suspended such privileges for Houston’s traveling fans.