The Spain midfielder hit a brace at Anfield in March 2015, including a superb scissor-kick volley.
But while his manager Jose Mourinho just deemed it another important game in the run up to Saturday's match, Mata ranks the United-Liverpool rivalry above games such as the north London derby between Tottenham and Arsenal, as well as the Manchester derby.
"It is the biggest game for both teams and maybe in English football as well," Mata told MUTV, "The rivalry, the history of both clubs and the atmosphere as well.
"Any game against Liverpool is special and, if you are able to score a fantastic goal or have a great performance, it will be remembered forever.
"I think if you ask fans what my best moment at United is, it would probably be that game and, specifically, that goal.
"It was a fantastic day for me: playing at Anfield, scoring twice and scoring the winning goal."
United host Liverpool on Saturday on the back of a thrilling comeback win at Crystal Palace on Monday, Mourinho's men claiming a 3-2 victory thanks to a late Nemanja Matic screamer.
"It was a tough game," Mata said. "We were lucky to come back after being 2-0 down, especially playing away from home. The result was a great boost of confidence as well as beating Chelsea the week before.
"Liverpool are a good team. Everything is going quite well for them, especially with their attacking players. They're scoring a lot of goals especially from Mohamed Salah, who's having a fantastic season. We need to be ready for them.
"Every player prefers to play at home. We need to make that count. We are at Old Trafford, where we feel comfortable, and we need to give 100 per cent to create an atmosphere for the fans."