Liverpool have recorded their second English Cup win over a Manchester football side in one week, a Dirk Kuyt goal enough to see off visitors Manchester United 2-1 in the FA Cup fourth round.
Substitute Kuyt struck two minutes from time to give the hosts the fourth-round win with visiting captain Patrice Evra - who Reds fans blame for Uruguayan striker Luis Suarez's eight-match ban for racial abuse - being booed throughout and making a mistake for the goal.
Andy Carroll flicked on the ball to leave the French left back Evra out of position and Dutchman Kuyt slammed in when David De Gea could again have done better - the struggling United goalkeeper had earlier failed to collect after being deliberately crowded out when Liverpool, still missing the verve offered by forward Suarez, took the lead on 21 minutes through a Daniel Agger headed corner.
United, without the injured Wayne Rooney, hit back through a crisp strike inside the near post from Park Ji-sung on 39 minutes and the visitors had other good chances.
Liverpool were joined in the last 16 by Chelsea who won 1-0 at Queens Park Rangers earlier in another game where racist abuse allegations clouded the affair.
Liverpool made the League Cup final against Cardiff by beating Manchester City on Thursday.
In two all-Premier League ties, Bolton overcame Swansea City 2-1 at home and Norwich City prevailed 2-1 at West Bromwich Albion to also make round five.
Last season's runners-up, Stoke City, progressed with a simple 2-0 victory at Derby County.
Leicester City beat Swindon Town 2-0, Sheffield United were humbled 4-0 at home by Birmingham City, and Stevenage saw off Notts County 1-0.
Other results included Blackpool drawing 1-1 with visitors Sheffield Wednesday, while Millwall also face a replay after drawing by the same score with Southampton in London.