Fans of Triestina, a professional soccer team from the northern Italian city of Trieste, were greeted with a surprise Saturday when they arrived at the team's stadium for a game against Padova.

For the first time in four years, nearly every seat in the "Colaussi" stand, which runs along one side of the field and faces the television cameras, appeared to be taken. That stand alone, which holds 10,000 fans, would have nearly doubled the team's average attendance from the previous year.

On television, the crowd looked impressive. But in person, the scene looked a bit strange. The fans were clad in scarves and winter coats—unusual for a balmy September afternoon. They failed to make a sound when the home team ran out on the field and didn't budge when the match ended in a scoreless draw.

Turns out there was a good reason for this: These "fans" were actually two-dimensional images of fans printed on a giant sheet of vinyl and stretched across the empty seats.

"It's a virtual tribune, with virtual fans," says Marco Cernaz, Triestina's general manager. "We'd love to have a full stadium with real supporters. And we've done everything we can to get people through the gates. But the reality is that we can't. This way at least we create a bit of atmosphere, a bit of theater."

If you've ever showed up to a major sporting event only to be bummed out by the sight of empty seats, take heart. The Italians are on the case.

In a bid to improve the ambience, make its games look better on TV, earn a little extra advertising revenue and save a little money on game-day operations, Triestina has installed what is believed to be the sports world's first "virtual crowd." The team won't say how much it paid to produce and install the PVC covering, which features images of real Triestina fans, but between the money the team will save by eliminating stewards, attendants, medical staff and insurance for the shuttered seats (about $130,000 per season) and the extra ad revenue it may earn, team owner Stefano Fantinel says the experiment "will pay for itself very soon."

Triestina, which plays in Serie B, the second tier of Italian soccer, has some serious challenges when it comes to selling tickets. Trieste is in a geographic cul-de-sac, with the Adriatic Sea to the south and west, Slovenia to the east and a narrow strip of land connecting it to the rest of Italy. That means the city, despite a population of some 200,000, has virtually no surrounding population. "We're also the oldest city in Italy demographically, with an aging population and one of the lowest birth rates in the country," Mr. Fantinel says.

Legislation introduced over the past two years to curb hooliganism now mandates that fans must present identification when buying tickets and, in some cases, do so in advance. What's more, every Serie B game is broadcast on live TV, a fact that may also limit crowd sizes (Serie B attendance has fallen almost every year since 2002). On Saturday, Triestina drew just 4,546 fans in a stadium that holds a total of 32,454.

"We have one of the best stadiums in Italy, but we can't fill it and we can't make it smaller," Mr. Fantinel says. "So we came up with something like this."

Triestina isn't the first team to take drastic measures to deal with empty seats. In the U.S., the Oakland A's and Florida Marlins have employed giant tarps to cover sections of unsold seats in the upper decks of their stadiums (the only difference is that they don't have pictures). In the NFL, where a number of teams struggle with attendance, there's a longstanding and controversial rule that prevents games from being shown locally unless the team sells enough tickets.

Triestina hasn't stopped trying to fill seats with real people. Season-ticket prices start at the equivalent of $45 a seat, and Triestina runs frequent promotions: One recent link-up with a local supermarket chain allowed anyone buying more than $19 worth of groceries to buy a ticket for the opening game for just $1.30. Still, attendance has remained flat over the past six seasons, oscillating between 5,600 and 6,900 per game.

Like an NFL team, Triestina doesn't have to sell out to survive. The team gets enough revenue from television (about 70%) to stay afloat. But that didn't make Triestina's move any easier for its fans to swallow.

"It's depressing," says supporter Marco Caselli. "It's as if we're sending out the message that Trieste has no flesh-and-blood fans, just cardboard cutouts."