Chelsea saw a 2-0 half-time lead disappear as Southampton fought back to draw 2-2 at Stamford Bridge in the Premier League.
Demba Ba, starting ahead of Fernando Torres once again, gave the hosts the lead, and Eden Hazard looked to have set the Blues towards a comfortable win when he struck on the cusp of half-time.
But substitute Rickie Lambert headed a goal back for the visitors with his 10th Premier League strike of the season, and Jason Puncheon's thumping half-volley with a quarter of an hour to play sealed the comeback.
The pressure on beleaguered interim manager Rafa Benitez will mount after another disappointing home performance, which sees the Blues waste a chance to close up on Manchester City in second and pull clear of Tottenham in fourth.
The Chelsea boss made just one change from the side which had beaten Stoke convincingly at the weekend, with Oscar replacing Ryan Bertrand in midfield.
Southampton, for their part, were able to retain rising star Luke Shaw despite an injury scare in the win over Aston Villa, but left Gaston Ramirez and weekend goalscorer Lambert on the bench.
If truth be told the home side were limp for much of the first half, despite their eventual lead – Oscar in particular was conspicuous by his poor touches in freezing conditions in London – and Southampton, if not threatening much, were certainly comfortable on the ball.
They had the best of the early chances, with Puncheon rising high above Ashley Cole to meet a Guly do Prado cross, only to head wide when he should have hit the target.
Chelsea were not so wasteful, and Ba bagged the opener when he hooked in a deflected cross from Cesar Azpilicueta in an instinctive finish.
Still Chelsea did not burst into life; instead, it was the visitors who could have struck next, with Steven Davis shanking wide after being played in by Jay Rodriguez’s superb control and lay-off.
That chance gone, Chelsea went forward, and laid siege to the goal for the final five minutes of the half.
Frank Lampard went close twice in a couple of minutes, Hazard and Oscar almost combined to bundle the ball over the line, and Ramires clattered the upright.
Southampton could not hold out, and Hazard got on the scoresheet when he followed up Ramires’s effort and hit a left-footed half-volley beyond Artur Boruc.
The second half should have been plain sailing, but shortly after Nigel Adkins introduced Lambert for Rodriguez, the Saints secured a lifeline.
Nathaniel Clyne powered down the right, and delivered a cross that Lambert nodded in at the near post.
There was just over half an hour remaining, but Chelsea seemed unnerved by the goal, and their visitors emboldened.
Despite that, the Blues still had their opportunities to put the game to bed – Juan Mata’s sensational weighted through ball was almost brilliantly volleyed in by Ba, while Lampard whipped a free-kick just wide of the upright.
Exposed to the counter-attack, Chelsea were picked off by a scintillating run down the left from Shaw, who crossed across the edge of the penalty area. Puncheon took a touch to tee himself up, before lashing into the far corner.
Benitez threw Torres on for Lampard, but the misfiring striker now has just one Premier League goal for the Blues in 20 appearances as a Premier League substitute for Chelsea. He did come closest to finding a winner, drilling low but wide from the edge of the area as space opened up in front of him.
Chelsea needed a finish to the second half to match the way they ended the first - but their balls forward grew more speculative, and Jos Hooiveld in particular was on hand to keep clearing the ball out of harm's way and seal a precious point in the Saints' bid for safety.
MAN OF THE MATCH
Jos Hooiveld - Southampton: Held things together for Southampton, and was calm and composed as the Blues threw bodies and long balls forward late on.
Chelsea: Cech 7, Azpilicueta 6, Cahill 7, Luiz 6, Cole 5, Ramires 6, Lampard 6, Oscar 5, Mata 6, Hazard 6, Ba 8. Subs: Torres 7.
Southampton: Boruc 7, Clyne 7, Yoshida 7, Hooiveld 8, Shaw 7, S Davis 7, Schneiderlin 6, Cork 7, Puncheon 7, do Prado 7, Rodriguez 6. Subs: Lambert 8, Ramirez 6, Chaplow 7.