Sir Alex Ferguson admits the emotion of the occasion of this weekend's clash between Liverpool and Manchester United could affect both sets of players.
Sunday's showdown at Anfield will be Liverpool's first home game since the recent publication of the Hillsborough Independent Panel's report into the 1989 tragedy where 96 Liverpool fans were crushed to death.
Ahead of what is likely to be a highly-charged affair on Merseyside there have been calls for several parties for respect to be shown to the victims and families of the Hillsborough disaster.
Ferguson believed the circumstances of the match would make it difficult for both sides, likening it to the game his side played against Manchester City at Old Trafford in February 2008 just days after the 50th anniversary of the Munich air disaster in which eight United players died.
"It is possible (that the build-up could affect players). Human nature is that way," Ferguson said.
"It happened to us at the 50th anniversary of Munich. We were so flat. We just wanted to get it out of the way (United lost that match 2-1)."
Asked about how both clubs had handled the build-up to Sunday's game, Ferguson said: "We have done our bit. Liverpool have done their bit. The messages have been said.
"There is enough pressure on the players. It is an important game for both clubs."