"This will be the biggest crowd at Deepdale for years and everyone is looking forward to it," said Mellor.
"It's exciting for the players and the fans. This is our biggest game in 20 years so that shows you what it means to the people of Preston. It's going to be our Cup final.
"We have the Bill Shankly Kop here at Deepdale which the club have given to the Liverpool supporters, so that is special as well.
"The FA Cup third round is a massive thing for me as I love the competition. Playing against Liverpool will be strange for me but also exciting.
"I learned my trade at Liverpool under Hughie McAuley and Steve Heighway and managed to play for the first team and score in front of the Kop.
"Liverpool is such a special club and I will always look out for their results.
"I really hope they win the Premier League this season and I certainly believe that they can."