Chelsea moved up to second in the Premier League with a 5-1 win over ten-man Southampton.
The much-changed Chelsea side took the lead inside seven minutes through a close-range header from Axel Disasi but the advantage was soon wiped out by Joe Aribo as the Saints started the brighter.
An error from the home side helped Christopher Nkunku regain our lead and then Noni Madueke curled in a third to make it four goals with only 34 minutes on the clock.
A lapse in judgement from Jack Stephens saw the Southampton captain sent off for pulling Marc Cucurella's hair prior to half-time and the Blues were able to round off a memorable night with further goals from Cole Palmer and Jadon Sancho in the second half.
Seven changes
Enzo Maresca made seven alterations to the team that beat Aston Villa 3-0 on Sunday, with Filip Jorgensen starting in goal for the first time in the Premier League and the back four consisting of Malo Gusto, Disasi, Tosin Adarabioyo and Marc Cucurella.
Moises Caicedo was back in his more traditional role of centre midfield alongside Enzo Fernandez, with Cole Palmer also retaining his place in a more advanced role, and Joao Felix and Madueke on the left and right flank respectively.
Nkunku, who already has 12 goals this season, was starting in the Premier League for the first time since the opening day of the season, as Nicolas Jackson took his place on a bench that also included Romeo Lavia, Pedro Neto and Jadon Sancho, to name a few.
Chelsea had a near miss inside the opening two minutes as Jorgensen made a fine save to deny Aribo from close range. The offside flag went up but video replays seemed to suggest the Saints man was on-side.
Quick-fire goals
But it was the Blues who went ahead on seven minutes when Fernandez's corner to the near post was met by Disasi, who headed in from a matter of yards out under minimal pressure.
The lead lasted a matter of minutes though as Aribo got his goal. Kyle Walker-Peters was a little fortuitous when a tackle rebounded into his path on the byline and his pullback was met by the arriving Nigeria international who volleyed into the bottom corner.
The Saints had enjoyed the brighter start but Chelsea once again took the lead just after the quarter of an hour mark. When Joe Lumley, who was well outside the penalty area, passed to Walker-Peters, great anticipation from Madueke saw him nip in front of the full-back and when the goalkeeper attempted to close down the England winger, he passed to the unmarked Nkunku and the Frenchman was left with a simple finish into the empty net.
Chelsea were much improved after the goal and would have scored more soon after had it not been for some great saves from Lumley.
The former QPR keeper denied Madueke with a good stop from close range before making a superb one-handed save to deny Palmer when one-on-one, following a fine pass from Felix, who had himself shot wide a minute earlier.
When Tosin did finally beat Lumley with a header from Palmer's corner, the home side were saved by the crossbar.
Game-changing five minutes
Chelsea's third goal finally arrived on 34 minutes and in impressive fashion. Some fine team play, including a great pass from Palmer, ended with Felix passing to Madueke on the right wing and he shifted the ball on to his left foot ten yards out and picked out the far bottom corner.
Then came a moment which completely changed the dynamics of the contest. In the build-up to Southampton taking a corner, Stephens pulled the hair of Cucurella and after referee Tony Harrington had checked the VAR monitor, the centre-back was given a straight red card.
Chelsea went close to adding a fourth in first-half injury-time when Madueke's in-swinging cross from the right was met by Joao Felix sliding in at the far post but his diving effort went wide.
Joao Felix should have scored 30 seconds into the second half. The Portugal international was completely unmarked at the back post when he was picked out by Madueke but his header back across goal went wide of the post.
Chelsea had another two glorious chances to increase our lead within ten minutes of the second half starting. First Tosin rattled the near post from close range following another dangerous corner from the left and then when Palmer had a shot spilled by Lumley, it looked as though Madueke was destined to score the rebound but Ryan Manning produced a goal-saving block to keep it at 3-1.
Southampton continued to fight and sent a warning shot moments later when they countered and Aribo's low cross was sent goalwards by Mateus Fernandes. But the outstretched leg of the diving Jorgensen kept the advantage to two goals.
Both teams kept searching for the game's fifth goal and some fine build-up play saw Madueke force Lumley into good saves twice in a matter of minutes.
Chelsea's fourth goal finally arrived in the 77th minute when Fernandez's through-ball picked out Nkunku and after a neat turn in the box, his shot was trickling towards the goal when Palmer made sure and applied the finish close to the goal-line.
And a fifth followed ten minutes later when substitute Sancho was left free on the right-hand side of the penalty area and he smashed the ball past Lumley at his near post.
Chelsea's fans sung throughout at St Mary's and as the game drew to a conclusion, there were continued chants of 'Enzo Maresca' as the travelling supporters celebrated another memorable away day.
What it means
Chelsea's emphatic victory and Arsenal's later kick-off against Manchester United means the Blues are now up to second.
Liverpool continue to lead the Premier League but their 3-3 draw with Newcastle United means their lead at the top of the table has now reduced to seven points.
What is next
Chelsea now head to Tottenham Hotspur Stadium on Sunday for the eagerly-anticipated London derby with Spurs, who are just down the road in Bournemouth tomorrow night.
The teams
Chelsea: Jorgensen; Gusto, Disasi, Tosin, Cucurella (Veiga 79); Caicedo, Fernandez (c); Madueke (Sancho 72), Palmer (Dewsbury-Hall 79), Joao Felix; Nkunku
Substitutes not used: Sanchez, Badiashile, Colwill, Lavia, Neto, Jackson
Goals: Disasi 7, Nkunku 17, Madueke 34, Palmer 77, Sancho 87
Southampton: Lumley; Walker-Peters, Bree, Stephens, Wood, Manning; Fernandes, Aribo; Armstrong (Diaz 62), Archer (Sugawara 72), Fraser (Sulemana 61)
Substitutes not used: McCarthy, Edwards, Taylor, Cornet, Amo-Ameyaw, O'Brien-Whitmarsh.
Goals: Aribo 11
Bookings: Armstrong 47
Red card: Stephens 39
Referee: Tony Harrington
Crowd: 31,193