Liverpool's success in the English Premier League which sees them sit second on the table hurts Wayne Rooney, according to the Manchester United striker.
Liverpool lie seven points behind leaders Chelsea - albeit with a game in hand - while Manchester United are sixth with 48 points, 11 behind their Merseyside rivals. Rooney, who joined United from Everton in 2004, has won 10 of his 17 games against Liverpool.
Brendan Rodgers' side visit Old Trafford on Sunday.
"To see City doing well, and particularly Liverpool, is really difficult," Rooney told Inside United. "It's not nice when we know we are capable of being up there challenging and we haven't been doing that this season.
"However, it means we have to step up and get back up there because the feeling we've had this season is not a nice feeling at all to have."
After winning the league last year, Manchester United's new season has not gone according to plan.
Under new manager David Moyes, United are almost certain to lose their league crown and have been knocked out of the League Cup and the FA Cup. Moyes' side lost their last-16 Champions League first-leg to Olympiakos 2-0.
"Hopefully we can make the top four but, if not, we will still come back firing for next season."