Liverpool knocked Aston Villa out of the FA Cup following a hard-fought 4-1 victory at Villa Park, avenging their humiliating loss at the venue earlier in the season.Sadio Mane bagged a brace while Mohamed Salah and Georginio Wijnaldum scored a goal each for the reigning Premier League champions.With the first-team squad ravaged by COVID-19 infections, the home side were missing all their key performers and were forced to play a group of young and inexperienced players.However, they still managed to put up a great challenge, especially in the first half, with Louie Barry even equalising just before half-time.The gulf in quality between the sides eventually showed, and Jurgen Klopp's men saved themselves the blushes with a second-half blitz.Here are the Liverpool player ratings from the fixture:Liverpool player ratings against Aston VillaCaoimhín Kelleher - 7/10If it hadn't been for the Liverpool defence getting horribly exposed on the break, this would've been a clean sheet for Caoimhín Kelleher. The 22-year-old won't have an easier night than this to make his mark for the Reds.Neco Williams - 6/10With little to do at the back, Neco Williams drove forward at will and connected well with Curtis Jones and Mo Salah on the right, even laying two key passes for Liverpool.Rhys Williams - 6/10Rhys Williams was outpaced by Louie Barry on the break leading up to the equalising goal. Apart from this, the 19-year-old was sound and completed 92% of his passes in the game.Fabinho - 7/10Fabinho held his ground well and tried to build from the back. He also registered the highest pass completion rate of all players, with a 96% success rate.James Milner - 7.5/10James Milner turned back the calendar with a solid display, making the most touches (143), creating the most chances (4) and completing the most tackles (4) in the game.5 - Five of Aston Villa's starting XI (Sylla, Hayden, Barry, Bogarde, Chrisene) weren't even born when James Milner made his debut in the FA Cup in January 2003 for Leeds United vs Scunthorpe. Opportunities. pic.twitter.com/7SAw1vH084— OptaJoe (@OptaJoe) January 8, 2021Curtis Jones - 7/10Curtis Jones put in an impressive performance for Liverpool and registered yet another assist for the side. The Reds' rising star laid a superb cross for Sadio Mane, who scored a header to put the visitors in the lead.Jordan Henderson - 6/10Jordan Henderson struggled for control in the midfield and was taken off at half-time for Thiago. It was not the best night for the Liverpool captain.Georginio Wijnaldum - 7/10Georginio Wijnaldum restored Liverpool's lead in the second half with a tidy finish, marking only his second goal of the season and triggering the late onslaught.Mohamed Salah - 7/10Mohamed Salah struggled to get to the end of crosses in the first half. However, he found the back of the net in the second with a simple finish.Sadio Mane - 8/10Sadio Mane registered yet another brace for Liverpool. Both goals came through well-taken headers as the Senegal international extended his goal tally to nine for the season.Takumi Minamino - 6/10Takumi Minamino helped Georginio Wijnaldum to put Liverpool back in the lead. Until then, however, he was largely quiet.SubstitutesXherdan Shaqiri - 8/10Xherdan Shaqiri had more impact in 30 minutes of play than in the entirety of the 2020-21 season thus far, laying two beautiful assists for Sadio Mane and Mo Salah in quick succession.2 - Xherdan Shaqiri is the first Liverpool player to assist two goals as a substitute since James Milner vs Spartak Moscow in December 2017 (3) and Shaqiri assisted those two goals within 208 seconds of coming off the bench. Impact. pic.twitter.com/tJyJivStfL— OptaJoe (@OptaJoe) January 8, 2021Thiago - 8/10After Thiago arrived at half-time, the Reds were more fluid and free-flowing than ever before. Co-incidence? We think not.Roberto Firmino - 6/10Roberto Firmino replaced Curtis Jones at the hour mark but couldn't really influence the proceedings.Alex Oxlade-Chamberlain - 6/10Alex Oxlade-Chamberlain had a forgettable cameo for the midfielder and was barely seen during the final quarter of the match.Divock Origi - 6/10He came alongside Oxlade-Chamberlain but struggled to make an impact.