The on-loan Chelsea forward has played twice for the Reds since joining the club at the beginning of the month.
He told Sky Sports: "It is a massive rivalry between two great sides.
"We are looking forward to it at the same time. It is not going to be an easy game for us but we will do our best to make sure we get the win.
"Whenever United play Liverpool, it is always a massive game which anyone in the world would like to watch.
"Now I am a Liverpool player, you have to look forward to it and hopefully we can win the game.
"It is always a good feeling to go out at Old Trafford and win games. But it is not easy to go there and win any game.
"United have a great record at Old Trafford. If we can go there and beat them, it would be one of the best feelings in any footballer's career."