Just when a disappointing afternoon for Tottenham ostensibly could not get any worse, Harry Kane limped off down the tunnel 15 minutes from time clutching his left hamstring, with Spurs succumbing to the fourth league defeat of José Mourinho’s reign after another powder-puff performance.

It was at that point Mourinho, irked by his side’s flimsy display and Kane joining the £55m record signing Tanguy Ndombele in prematurely trudging down the tunnel, decided to take matters into his own hands, wandering over to the Southampton dugout to insult the goalkeeping coach, Andrew Sparkes – an act of petulance that earned him a booking from the referee, Mike Dean.

José Mourinho calls Southampton coach ‘an idiot’ and attacks VAR power Read more

In some ways Mourinho was only just warming up, later accusing the Southampton ballboys of time‑wasting before sticking the boot into Ndombele for being injury prone after the midfielder was forced off midway through the first half. Mourinho’s six-minute post-match press conference was box office but the Portuguese’s personal attack on a member of Ralph Hasenhüttl’s backroom staff stunk of deflecting from another abysmal away performance, a second defeat on the road in four matches.

For Southampton this was the latest episode to cherish across a brilliant Christmas period, with victory here lifting them towards mid-table after a return of 10 points from a possible 12.

Familiar flaws marred Tottenham’s first outing of the new year, with Danny Ings fooling Toby Alderweireld to continue his extraordinary form in front of goal. It made painful viewing for Mourinho, who reacted to being booked by apologetically patting Dean’s torso, powerless as another side pierced holes in a frail defence that has kept one clean sheet since he took charge in November. Under Mourinho, Spurs have lost four of their nine league matches and, after stuttering to a draw at Norwich last weekend, this was a meagre retort.

Take nothing away from Southampton – Ings took his goal superbly – but Spurs were carved open too easily. Jack Stephens played a simple ball over the top and Ings allowed it to bounce before nonchalantly flicking it inside Alderweireld with his right foot and instinctively stroking home beyond Paulo Gazzaniga with his left. Gazzaniga was beaten and Alderweireld humiliated, with the former Southampton defender skidding away on the turf on all fours as Ings lashed in his ninth goal in as many league starts, taking his tally to 13 for the season.

Tottenham surrendered possession cheaply in the first place, with Ryan Sessegnon’s panicked pass from left‑back landing at Stephens’s feet. To make things worse, Ndombele was clipped by Stuart Armstrong in the buildup to the goal, leading to Giovani Lo Celso replacing the Frenchman, who has struggled for match fitness since signing from Lyon. Stephens’s ball downfield was simple but Ings showed wonderful composure to finish.

Facebook Twitter Pinterest Danny Ings clips the ball over Toby Alderweireld before scoring Southampton’s winner against Tottenham. Photograph: Ian Walton/Reuters

“It’s unbelievable at the moment,” Hasenhüttl said. “If he has a chance, he scores. He is full of self-confidence.”

Tottenham’s resistance was feeble and Southampton would have doubled their lead but for a crucial interception by Alderweireld after Nathan Redmond latched on to Armstrong’s low cross from the right. That move in itself typified and exuded everything a lacklustre Tottenham side seemed to be missing, with Armstrong doing brilliantly to juggle and keep the ball in on the touchline before supplying Redmond with an inviting cross. Armstrong’s work-rate was relentless but it was another mightily convincing team performance, a world away from that 9-0 defeat here in October.

“A really fantastic start to this year,” Hasenhüttl said. “Maybe the best performance at home this season so far. We were so aggressive, so committed against the ball and it was very, very difficult to create chances against us.”

Spurs lacked rhythm and seemed disjointed from back to front. Hasenhüttl’s side kept them at arm’s length throughout and the only whiff of Alex McCarthy’s goal came when Kane swept home a Christian Eriksen free-kick, only for the assistant referee to raise his flag. Tottenham’s celebrations were quickly curtailed and Kane’s match was soon over, with the striker injuring himself as he took aim inside the box.

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In the first half Southampton also survived a VAR check when Alex McCarthy clashed with Dele Alli after scrambling Kane’s powerful shot to safety. From the resulting corner Jan Vertonghen scooped over unmarked and, four minutes from time, Lucas Moura’s effort went out for a corner after smacking Ryan Bertrand on what proved a thoroughly miserable day all around for Tottenham.