However, the 30-year-old thinks the champions can retain their title and refuses to rule Chelsea out of the title race as he prepares to head to Stamford Bridge
So far this season, Sir Alex Ferguson's side have failed to reach the last 16 of the Champions, have been knocked out of both the FA Cup and League Cup and are behind Manchester City in the race for the Premier League title.
The 30-year-old revealed that he thinks the rich history surrounding the Red Devils has made the fans become too expectant, but insists the team are still able to challenge Roberto Mancini's side.
He told reporters: "It might be that before we scored a lot of goals and that has a big impact on the fans.
"Their expectations become too high. Maybe also because we are out of the Champions League and the FA Cup, people think Manchester United is no good.
"But we can show our strength on the pitch. We are still producing good performances, we are level with Manchester City and can still win the title."
The champions have also been hit by injuries to key players with the likes of Nemanja Vidic, Darren Fletcher, Tom Cleverley, Anderson and Ashley Young all missing large chunks of the season. However, the South Korean stressed that this highlights the strength of their squad.
"It is part of our history," Park said.
"Last season we had a lot of injuries as well but we kept doing well and we won the title.
"It shows how strong our squad is, that we are able to deal with this kind of problem.
"Everyone has a good mentality. When we get these injured players back, they can help us fight to win the league."
Park scored in United's fourth-round FA Cup loss against Liverpool and he is hoping to continue scoring against the big clubs with the Red Devils facing a tough trip to Stamford Bridge on Sunday, while he has not ruled Chelsea out of the running for the title yet.
He added: "It always feels good to score goals against big teams
"But I am just trying to help the team to win. It doesn't matter how many I get."
"When I look at the table, it is different.
"But when I play against Chelsea, I don't consider them as being out of the title race. They are still our rivals.
"I know the points gap between Manchester City and Chelsea is quite a lot but they won't give up until the end of the season. They will always try to fight.
"I don't feel there is any difference with Chelsea compared to previous seasons."
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