Manchester United vs Barcelona is perhaps the most exciting of all four Champions League quarter-final ties. On Wednesday night the La Liga leaders visit Old Trafford for the first leg, with the return fixture being played six days later. With Lionel Messi and co. in town to face-off against a Premier League side, it's expected that millions of people around the world will be tuning in to watch. It will be one of Old Trafford's biggest European nights and those in the stadium that get to experience the match will surely remember it for years to come. But incredibly, the ground won't be at full capacity - because there will be a lot of empty seats in the away end.

According to Chris Slater of the Manchester Evening News, only 2000 Barca fans will be making the trip as the club has failed to sell out their 3500 seat allocation. 

"I'm told Barcelona haven't yet sold their full allocation of 3,500 tickets for their Champions League game at Old Trafford on Wednesday," Slater tweeted.

"MUFC are expecting around 2,000 to make the trip."

For a game as big as this, it's very surprising that Barca failed to sell out the away section - but Man United could have actually played a big role in that. 

Last month it was revealed that tickets for the return leg at Camp Nou would cost United supporters £102. 

Unhappy with that 'excessive' price, the English club decided to charge the same for an away ticket at Old Trafford. 

United now plan to use that extra money to subsidise ticket prices for their own fans next week, meaning travelling supporters will only pay £75 in Spain. 

With Barca fans being charged over £100 for a seat as a consequence for their own club's high prices, it's less surprising that they've failed to sell out.