Preston North End striker Kevin Davies has expressed his belief that Manchester United are failing to live up to expectations under manager Louis van Gaal.

The Dutchman has restored United's place amongst the top four in the Premier League following a disastrous spell under David Moyes, but there have been increasing murmurs of discontent from fans in recent weeks.

Van Gaal himself admitted that he was concerned by the supporters' frustration during Wednesday's 3-1 victory over Burnley, and Davies, whose Preston side face the Red Devils in the FA Cup on Monday, believes that some of the team's key players are not enjoying their football.

"I've got quite a few friends who were at the game last night. Obviously they're pleased to be back in amongst the Champions League but there have been a few boos about the long balls and the style of play has not been great. They've spent money and they should be contesting those Champions League spots," Davies is quoted as saying by PA.

"In terms of watching them, I don't think they're as exciting as they used to be but, when you lose someone like Sir Alex Ferguson, it's always going to take time. They've got a bit of resilience about them. Not playing well and winning games you have to have. He's not had a settled side, there's been a lot of injuries. I don't think he's quite found the right system. Just looking at one or two of the players, like [Robin] Van Persie scoring last night, no real smile, he didn't look particularly happy. Wayne Rooney playing a bit deeper.

"It's probably different to what those players are used to. Players don't particularly like change anyway but a new manager comes in, new ways, are they enjoying it as much as they used to? I don't get that impression from the players. But you have to do the job that the manager asks of you. They're fantastic players but I don't think they're living up to expectations."

United travel to Deepdale on Monday looking to earn a place in the quarter-finals of the FA Cup.