The Football Association has defended its choice of venues for the FA Cup semi-finals amid slow ticket sales.
Watford are reported to have 1,500 tickets left unsold for Saturday's semi-final against Manchester United at Villa Park.
Blackburn and Chelsea, who meet at Old Trafford on Sunday, have both failed to sell 8,000 seats of their allocations.
An FA spokesman said: "Old Trafford and Villa Park are established venues, used to dealing with the logistics."
United are the only club to have sold out their allocation for the semi-final at Villa Park, which has a capacity of 42,000.
Old Trafford's capacity has been reduced to 70,900 for Sunday's game because of segregation requirements.
Blackburn's failure to sell their allocation of 30,900 is all the more surprising given that Old Trafford is only a 37-mile trip for their fans.
We feel the ticket prices are fair
But Mike Graham, of the Blackburn Independent Supporters' Association, blamed the cost of tickets.
"Our catchment area is basically just Blackburn, which is a small town," he told The Times.
"It's also a low-wage area. Even forking out the minimum of £25 per ticket is a lot, never mind the maximum £55."
Chelsea fans, meanwhile, are upset that they face a long trip to Manchester for a 1600 BST kick-off on Sunday.
However, the FA argues that even if Old Trafford is not full, it will still mean more fans can attend the game than if it had been held elsewhere.
"The crowd will be bigger than at any other ground we could have staged the game," said a spokesman.
"We want to make these occasions accessible to the fans. We feel the ticket prices are fair, and are appropriate to staging a big semi-final."
From next year, the semi-finals will be held at the new Wembley Stadium, which has a capacity of nearly 90,000.
"We are confident we will see big crowds at Wembley for the semi-finals," the FA spokesman said.