The Brazil international has been out since the end of November with an ankle problem, while centre-back Matip has not played since the last meeting with United in October due to a knee issue – but both have trained this week.
Marcus Rashford is a major doubt for United after aggravating a back injury in midweek.
The striker, forced off shortly after being introduced as a substitute in the FA Cup win over Wolves, is unlikely to feature in Ole Gunnar Solskjaer's plans.
Liverpool provisional squad: Alisson, Alexander-Arnold, Gomez, Van Dijk, Robertson, Henderson, Wijnaldum, Oxlade-Chamberlain, Salah, Firmino, Mane, Adrian, Williams, Matip, Fabinho, Lallana, Minamino, Shaqiri, Origi.
Man Utd provisional squad: De Gea, Romero, Williams, Wan-Bissaka, Dalot, Young, Jones, Lindelof, Maguire, Shaw, Fred, Garner, Gomes, Matic, Chong, Pereira, James, Mata, Chong, Greenwood, Martial, Rashford.