The Reds captain was making his last home appearance for the Merseyside club on Saturday but was left disappointed as Palace recorded a 3-1 victory.
Despite Adam Lallana scoring the opening goal in the 26th minute, Brendan Rodgers' side came up short as Jason Puncheon, Wilfried Zaha and Glenn Murray piled on the goals much to the dismay of Gerrard.
Senegalese winger Mane struck in the 13th, 14th and 16th minutes to set up the emphatic triumph which kept the Saints seventh but with a chance to sneak into fifth if they can beat Manchester City next week and both Liverpool and Tottenham lose their respective fixtures.
Newcastle United's recent misery continued when they were beaten 2-1 by the already-relegated QPR at Loftus Road.
Emmanuel Riviere struck first for the Magpies but second-half goals from Matt Phillips and Leroy Fer condemned the north east club to their ninth defeat in their past 10 outings which could see them relegated next weekend if they fail to win at home against West Ham United and Hull City beat Manchester United.
Elsewhere, Spurs defeated the Tigers 2-0 at home thanks to goals from Nacer Chadli and Danny Rose, Everto overcame West Ham 2-1 at Upton Park courtesy of Romelu Lukaku's injury-time winner, Burnley and Stoke City drew 0-0 as did Sunderland and Leicester City which saw the Foxes stave off relegation.
On Sunday, Manchester City tightened their grip on second place with a 4-2 win over Swansea City in south Wales thanks to a Yaya Toure brace, while Arsenal drew 1-1 at Manchester United to fall five points behind City.
2014/15 Barclays Premier League - season scores