Sir Alex Ferguson has risen to the defence of Gerard Houllier, saying he cannot understand why some Liverpool fans have turned against him.
"Gerard would be the first to admit that their season has not come up to expectations, but having said that, I still find it extraordinary that some of the criticism should be so hostile and violent," he said.
"After all, here is a team involved in a ding-dong battle for fourth place in the Premiership and a Champions League spot. Relegation battlers get better support."
Ferguson feels that, as was the case when he took over at Old Trafford, Houllier is being haunted by Liverpool's past.
"For a decade Liverpool dominated English football and enjoyed outstanding success in Europe," he added.
"We at United felt the draught of that because we fell under the Anfield shadow to the extent that we endured 26 years without winning the championship.
"Competition for fourth place is close and when a team gets pulled back it's frustrating but surely that's what football is all about and I find it sad that an element of support turns nasty."