The Belgian international had double-figures in his sights after scoring in last week’s win at Newcastle and duly delivered with a smart one-on-one finish to level the score at 2-2 on 70 minutes.
Graziano Pelle had twice put the Saints in front, but Erik Lamela cancelled out his first effort shortly before the break.
Both teams pushed for a winner but that’s how it stayed at St Mary’s – leaving the standings as they were at start of play with us one place and one point above the Saints.
Head Coach Mauricio Pochettino made three changes for the journey to his former club. Goalkeeper Hugo Lloris made his return from a knee injury to wear the armband, Ben Davies stepped in for the injured Danny Rose in defence, while Paulinho missed the trip due to the imminent arrival of his child - Ryan Mason coming in.
It was a quiet opening period as both teams took their time to get to know each other with both goalkeepers only really being called into action to gather stray passes. As the midway point of the half ticked by, we started to gain the upper hand with some slick passing through midfield.
It was not until the 25th minute that we saw the first chance of note when Morgan Schneiderlin met a corner from James Ward-Prowse, which forced a fine low save from Lloris.
Soon after, though, the home side grabbed the lead in scrappy fashion. An unfortunate slip from Mason on the edge of his own box put Davies in an awkward position and he was unable to hold off Pelle, who was able to poke the ball past Lloris from eight yards.
Mason went close 10 minutes later after Chadli tied his marker in knots on the left before crossing for the England midfielder, who made good contact on a volley though it was blocked.
We started to look more of a threat in the final third and grabbed a leveller soon after. Eric Dier crossed brilliantly from the right and Lamela was on hand to turn the ball in despite the best efforts of Kelvin Davis in the Saints’ goal.
There were no changes at the interval for either side and Steven Davis arguably should have put the home side in front shortly after the restart when he was afforded time and space on the edge of our box but he dragged his shot well wide.
If Davis had been disappointed not to score with that effort, he would have been devastated five minutes later when he squandered an even better opening after fine work from Pelle and the lively Sadio Mane.
Lloris denied Nathaniel Clyne soon after as we found ourselves on the back foot with 30 minutes to play.
Chadli looked our most likely goal threat with some tricky running in the final third, but Lloris remained the busier of the two goalkeepers.
He was powerless to prevent the Saints going in front again soon after, though, when substitute Shane Long picked out Pelle and the Italian rose brilliantly to plant a header into the top corner.
We remained positive, however, and having laid on the perfect ball for the first goal, Dier delivered again with a well weighted through ball into the path of Chadli who slotted coolly past Davis for his second in successive games.
Unfortunately for Davies his return to the side was cut short as he left the action on a stretcher with what appeared to be a nasty shoulder injury as he tumbled with Mane.
The resulting change saw Vlad Chiriches enter the fray at centre-back with Vertonghen moving to the left.
You sensed that we might be able to find another dramatic late winner but the home side eventually pinned us in during the latter stages of seven minutes added time with a series of corners and free-kicks.
However, we held firm with Jose Fonte going closest with the final action of the match, his header just over from Eljero Elia’s corner.
Southampton: Davis, Clyne, Yoshida, Schneiderlin (Reed, 90), Fonte, Davis (Elia, 81), Mane, Ward-Prowse (Long, 62), Alderweireld, Pelle, Bertrand. Substitutes (not used): Gazzaniga, Gardos, Tadic, Targett.
Spurs: Lloris (c), Dier, Fazio, Vertonghen, Davies (Chiriches, 75); Bentaleb (Soldado, 88), Mason; Chadli (Dembele, 83), Eriksen, Lamela; Kane. Substitutes (not used): Vorm, Yedlin, Stambouli, Townsend.
Goals: Southampton - Pelle (29, 65). Spurs - Lamela (43), Chadli (71).
Yellow cards: Southampton - S Davis (65). Spurs - Vertonghen (31), Davies (34), Fazio (90+6).
Referee: Jonathan Moss.