Chelsea had been flying after their win at Tottenham on Sunday, which felt like a defining moment for Frank Lampard and the evolution of his young team. This was a crash back down to earth, further evidence of the west London club’s maddening inconsistency. Perhaps it is the price to pay for having a young manager and a smattering of academy products. Whatever the reason, Lampard knows he has to find a more even keel and soon.

Southampton’s win was perfectly judged and entirely merited, ignited by a special first-half goal from the 19-year-old Michael Obafemi and driven by their second-half threat on the break. Nathan Redmond scored the goal that made the points safe – he was a thorn in Chelsea’s side – but this was a team triumph, built on the no‑nonsense central defensive contributions of Jack Stephens and Jan Bednarek. The midfielders Pierre‑Emile Højbjerg and James Ward-Prowse were also excellent.

Chelsea have lost three of the last four Premier League games at home, this one following those against Bournemouth and West Ham – and they have drawn a blank on each occasion. They dominated the possession against Southampton yet their inability to prise them apart was a huge concern. It was one of those days when they could have played on and on and still not scored – once again, they lacked personality on the ball – and it was difficult to isolate a clear-cut chance that they created.

Chelsea’s Tammy Abraham of Chelsea is challenged by the Southampton defender Jack Stephens. Photograph: Chris Lee - Chelsea FC/Chelsea FC via Getty Images

Southampton’s first clean sheet in the league since mid-September came with a degree of comfort and Ralph Hasenhüttl could revel in what he described as the best performance of his tenure, one that was characterised by bravery on and off the ball. When Ward-Prowse said that Southampton had “played Chelsea off the park”, it was hard to disagree.

Southampton’s away form has been better than at home – they always tend to score – and, when they did so for the first time here, it was a goal to blow away the cobwebs. It had been an attritional start but Obafemi injected the pace and incision to have Hasenhüttl leaping out of his technical area in delight. Taking a pass from Højbjerg, Obafemi – who started as Hasenhüttl rested the in-form Danny Ings – sliced inside Kurt Zouma before curling a wonderful left‑foot shot into the far corner.

Southampton’s 4-4-2 was designed to be difficult to break down; they left precious little space between the lines and their work rate, starting from the front with Obafemi and Che Adams, was prodigious. Chelsea could not find the answers and they fed off scraps.

Alex McCarthy tipped clear from César Azpilicueta, although the Chelsea captain’s flick was going wide; the disappointing Callum Hudson-Odoi had a shot blocked by Stephens and Fiyako Tomori headed weakly after a short-corner routine. McCarthy was also called on to deny the substitutes, Christian Pulisic and Mason Mount, late on but they were regulation saves.

Lampard had stuck with the 3-4-3 system that added up to a tactical masterclass at Spurs. It did not work at all on this occasion and he switched to 4-3-3 for the second half, with Mount in an attacking midfield role.

Chelsea looked more urgent with Mount on the pitch but it was Southampton who carried the greater threat on the counter. Redmond was denied one-on-one by Kepa Arrizabalaga on 65 minutes and he had previously beaten Antonio Rüdiger to cross low for Adams at the far post. Tomori stretched to toe the ball away.

Redmond would not be denied and his goal came after a long and impressive sequence of passes from his team. Stuart Armstrong tried to get away from N’Golo Kanté only for the Chelsea midfielder’s challenge to send the ball over to Redmond at the far post and the winger guided home smartly.

Hasenhüttl celebrated wildly in front of the travelling support at full‑time, punching the air in the manner of his friend Jürgen Klopp, and the statistics show that it is four wins out of six for his team. Southampton, remember, had endured that 9-0 humiliation at home against Leicester on 25 October. Their revival gathers pace. “We played like a relegation team,” Hasenhüttl said. “Now we play like a Premier League team.”