Liverpool are within touching distance of the Premier League title after Virgil van Dijk sealed a dramatic 2-1 win against West Ham, while Tottenham manager Ange Postecoglou suffered more misery in a 4-2 defeat at Wolves.
Ange Postecoglou insists the person leaking information about Tottenham injuries and team selections is not one of his players
Ange Postecoglou's troubled side trailed to Hugo Ekitike's early goal in north London, but Pedro Porro hauled them level before half-time.
Southampton are still one point behind Derby County's 2007-08 record low Premier League points total of 11.
Tottenham are languishing in 14th place in the Premier League after a 1-0 loss at Chelsea.
Chelsea climbed to fourth place in the Premier League as Enzo Fernandez sealed a 1-0 win that piled pressure on beleaguered Tottenham boss Ange Postecoglou.
Chelsea badly missed the presence of the absent Cole Palmer due to injury as they meekly surrendered to a damaging defeat for their hopes of a top-four finish.
Two spot-kicks and a late arrowed finish from Fernandes sent Man Utd into the quarter-finals by a 5-2 aggregate margin against 10-man Sociedad.
Manchester United drew 1-1 away to Real Sociedad in the first leg of their Europa League last-16 tie on Thursday, while Tottenham suffered a 1-0 loss at Dutch side AZ Alkmaar.
Manchester United were drawn Friday to play Real Sociedad of Spain in the last 16 of this season's Europa League, while Rangers will take on Jose Mourinho's Fenerbahce, and Tottenham Hotspur face AZ Alkmaar.
Tottenham won the battle of the Premier League's underachievers 1-0 on Sunday to inflict another dismal result on Manchester United boss Ruben Amorim.
Liverpool suffered a stunning FA Cup exit on Sunday in a 1-0 defeat to Championship strugglers Plymouth
Liverpool overturned a first leg deficit to reach the League Cup final with a 4-0 win over Tottenham on Thursday
Former Barcelona midfielder Nico Gonzalez, 23, arrives for a reported fee of 60 million euros (50 million euros, $62 million).
Manchester United slumped to another meek home defeat as Crystal Palace won 2-0 at Old Trafford on Sunday, while Tottenham eased the pressure on Ange Postecoglou by beating Brentford 2-0.
Manchester United, unbeaten in eight games in the tournament, finished in third place and Tottenham came fourth, ensuring the Premier League clubs both avoided the Europa League play-off round.
Manchester United and Tottenham are among the sides aiming to ensure direct passage to the Europa League last 16 in Thursday's league phase finale with nine places in the knockout stages up for grabs
Leicester pushed Tottenham boss Ange Postecoglou closer to the exit door with a 2-1 win that extended Spurs' dismal run