Ange Postecoglou's men have been slain by Bournemouth and Chelsea in their last two top-flight matches, defeats that have plummeted them into the bottom half of the Premier League standings after 15 matchdays.
The Lilywhites could not exorcise their demons in a 1-1 Europa League draw with Rangers in midweek either, extending their winless run in all tournaments to five games since they stunned Manchester City 4-0 in November.
None of Spurs' established stars - including Son Heung-min - have been shining bright during their mediocre spell of form, but facing Southampton always seems to bring the best out of the Tottenham skipper.
Here, Sports Mole takes a closer look at Son's record against the Saints ahead of Sunday's top-flight match.
Son Heung-min's record vs. Southampton
Played: 17
Won: 10
Drawn: 4
Lost: 3
Goals: 12
Assists: 5
A perennial tormentor of Southampton ever since touching down on British shores, Son Heung-min enjoys facing the Saints more than any other team and averages one direct goal contribution per game against the South Coast side.
Indeed, the South Korea international has been involved in 17 goals in 17 matches against Southampton in all competitions, including 12 of his own, his best goalscoring tally against a single opponent in his senior career.
Son has also set up five goals in meetings between Tottenham and Southampton, his joint second-highest total versus a single team, having managed six assists - but fewer goals - against West Ham United and Everton.
Son's individual success in this fixture does not always translate into team glory, though, as seven of his 17 meetings with Southampton have seen Tottenham fail to come out on the winning side, drawing four and losing three of those contests.
Before Southampton's demotion in 2022-23, Son set up goals in both of Tottenham's games against them - including their 3-3 implosion at St Mary's - prior to which he netted a consolation effort in a 3-2 home defeat in the 2021-22 season.
However, the most memorable instalment of Son vs. Southampton undoubtedly came at an empty St Mary's in September 2020, when the South Korean scored four of Spurs' five goals - all of which were assisted by Harry Kane - in a 5-2 win.
That occasion marked the first time in Premier League history that a player had scored four goals in one game while being set up by the same teammate each time, and another one of Son's individual masterclasses against Southampton came on Boxing Day 2017, where he scored once and laid on two assists in another 5-2 success.
Outside of his 10 goals and five assists in Tottenham vs. Southampton Premier League meetings, Son scored in both of Spurs' clashes with the Saints in the 2019-20 FA Cup fourth round, winning and scoring the penalty that sealed a 3-2 replay win for Jose Mourinho's team.
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Written by
Ben Knapton