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Juventus are the last unbeaten side in Europe and have the star attraction of Cristiano Ronaldo wearing their famous black and white strip, yet it has been impossible not to notice the empty seats inside their stadium at home matches recently.

There can be no doubt this current side are among the favourites to win the UEFA Champions League, and it seems almost certain they will claim the Serie A title. So why the glaring gaps in the crowd?

The fixture against Chievo on January 21 was the most eyebrow-raising, with an official attendance of just 30,239. But even matches that are declared close to capacity seem to have big areas of unused seats.

"Juventus rarely play in front of a packed house," Juve fan and Bleacher Report writer Gianni Verschueren explained. "Both in Serie A and the Champions League, the Bianconeri struggle to sell tickets for matches against sub-elite competition. It's not a glaring issue, but combined with frequent protests from the ultras, it can make for a quiet stadium and results in plenty of photos of empty stands."

The Bianconeri left the famous 70,000-capacity Stadio delle Alpi—used for both athletics and football in Turin—after the 2006 season, and a purpose-built 41,000-seat stadium on the same site eventually became the club's home in 2011. The old stadium was never full, so it was decided that a smaller, packed home ground would be more beneficial.

On the big nights, it can be considered an arena worthy of one of the best clubs in the world, but there are issues holding them back from regular sellouts, as noted by Verschueren.

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"Pricing is the main issue," he said. "Juventus tickets were already expensive prior to Ronaldo's arrival, and the latest price hike has resulted in a major rift between the club and the ultras. Juventus' die-hard fans are not happy and have protested the club's policy on multiple occasions.

"Tourists have made up the difference to a certain extent, but Turin is not Barcelona or Madrid—there aren't nearly as many tourists. Add to that the departure of fan favourites like Gianluigi Buffon and Claudio Marchisio, and it's easy to see why attendance figures are suboptimal.

"Club members have priority over tickets, but Juventus' attendance issues result in plenty of tickets being available to day-trippers. As long as you're not trying to score tickets to a Champions League knockout match or the Derby d'Italia, you'll likely be OK. It doesn't hurt that Around Turin has established itself as a top-notch tool for day-trippers, acting as guides for international fans."

Around Turin is a go-to online destination for Juve fans across the world, with a huge social media following that guides supporters on every area of the club.

Founded by Maurizio, the aim is to make any trip to Turin a memorable experience, as fans are made to feel part of the club by meeting up with other supporters and being shown to the best spots in town to embrace Juventus life.

Maurizio explained to B/R why he believes there is difficulty in filling the stadium.

"First of all, you must know that the stadium has 41,000 seats and 29,000 of those are occupied by season-ticket holders," he said. "The season-ticket holders are considered even if they don't go.

"There are then 2,000 for away fans, 3,000-4,000 corporate seats...and this means that around 6,000-7,000 are available for the rest of the fans. The majority of season-ticket holders are travelling from outside Turin, so if the games are played on a Monday night, like Juve-Chievo, or the weather is poor, like for Juve-Parma, many fans might decide to avoid the trip.

"On top of that, the price of the tickets is also an issue. For example, for the game against Parma, there were many unsold tickets on general sales, but the price for those tickets was €160 (£140)."

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Home games with rock-bottom Chievo or 12th-placed Parma aren't the sexiest fixtures on the schedule, but still this is Juventus—a club with 180 million supporters across the globe.

Adam Digby, one of the leading English voices on Italian football, explained how the crowd is often bigger than it appears on television.

"We have to clarify what we're talking about when we say 'empty seats' at Juventus Stadium," he told B/R. "Because in the Curva Sud (the right-hand end behind the goal as you look on TV) is where the ultras are, and they don't sit in their allocated seats. It pushes more people into the centre of the stand, leaving a large space on the edges—which is always visible.

"That said, on the sides there are often many empty seats, particularly in Coppa Italia games or midweek matches against lesser opposition.

"A large number of season-ticket holders live outside Turin, closer to Milan than the stadium itself. If we take the recent clash with Chievo, played on a Monday night at 8:30 p.m., it's understandable that fans would choose to stay at home instead.

"Secondly, we need to look at the number of tourists who visit every week. It is a figure I would, after some research, peg at around 5,000 one-off visitors per game for sold-out matches. They too would shun a Monday night clash with Chievo, resulting in an attendance figure that was 30,239."

In England, Premier League champions Manchester City are regularly berated for failing to fill every seat, but the same comparisons are not made in Italy.

"There isn't the same 'banter' regarding empty seats in Italy as there is in England," Serie A journalist Chloe Beresford explained. "I think mainly because so many of the stadiums are bigger than necessary, and supporters of various clubs are used to the empty seats. A lot of that comes from Italia '90 when large stadiums were constructed to accommodate the FIFA World Cup.

"An example of this is the Stadio Marc'Antonio Bentegodi in Verona—an ugly concrete bowl that is nowhere near filled by either Hellas or Chievo Verona who play there. Therefore Juve's issue is not something that other fans would poke fun at, as it's nothing out of the ordinary in Italian football."

But let's come back to the star attraction here: Ronaldo.

When you sign a global superstar, a man many consider as the greatest of all time, you surely expect to sell out every matchday as well as shift millions of replica shirts bearing his name and number?

"His transfer has definitely brought more tourists," Digby said. "But what I think his move has done is increase the prices rather than attendance figures.

"There are more people wanting to go, but given that for most 'big' games, the stadium was sold out anyway, it has pushed people to go to some 'lesser' games—resulting in an average attendance this season of 39,217."

What may seem a problem from afar is actually not considered much of an issue at the ground. In fact, most fans are delighted to have a home that feels like the club's soul.

"We have to remember that Juve have historically struggled to attract fans to games," Digby added. "The club was averaging 37,000 fans during their 16-year stay at the Stadio delle Alpi, a ground which held up to 69,000 fans. That figure is why the club chose to build the new stadium on a much smaller scale.

"The new stadium has been welcomed—the Delle Alpi was awful. It was cold, empty and unwelcoming. The new stadium is very modern with a real Bundesliga feel to it, and the supporters who go enjoy it, even though compared to many Italian stadia, it might feel 'soulless.' It's much better than the previous experience at the Delle Alpi."