Chelsea responded to their humbling Premier League defeat against Brentford and Champions League setback against Real Madrid by blowing Southampton out of the water with a first half flurry.
Marcos Alonso fired Chelsea in front early on, and it was 3-0 inside 22 minutes as Mason Mount and Timo Werner found the net. Kai Havertz made it four just after the half-hour mark, with the home side all at sea defensively.
Southampton attempted to make some changes to gain a foothold in the game, but with no success. Werner and Mount both struck again within 10 minutes of the restart, and Thomas Tuchel was able to make changes of his own as the game wound down. Here, Mirror Football picks out five talking points as Chelsea prepared for the second leg of their Champions League quarter-final in the best possible way.
Mount back to his best
There have been plenty of differences between the first and second half of the season as far as Chelsea are concerned, and one of those relates to Mason Mount. The England international scored seven times before Christmas, but his strikes against Southampton were only his second and third since the turn of the year.
Mount looked up for things early on, providing the assist for Alonso's opener, but the best was yet to come. The first touch to set himself and the drilled finish into the corner of Fraser Forster's net were equally good, and it was one of those goals that only looks easy because the scorer has the quality to make it so.
His second goal was a little more straightforward, a close-range tap-in after some shaky home defending. However, he still had to make the right run to find himself in position to convert
If the 23-year-old can get into his groove again, it could serve Chelsea very well in the coming months. Who knows, it might even breathe some life into the Champions League campaign after his big contributions last term.
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Persistence pays off for Werner
Timo Werner was preferred to Romelu Lukaku in attack, and the German missed a golden chance in the opening minutes when he hit the bar from close range. However, there was encouragement in the fact that he was getting in the right positions.
Only a big hand from Forster denied him the next time, and that could have made him think it wasn't his day. However, after a mistake from James Ward-Prowse, the German raced through and kept his cool to round the keeper and finish calmly.
It was the kind of goal which wouldn't have looked out of place during Werner's RB Leipzig days. Remarkably, it was just his second in the league this season, with the first also coming against Southampton, while his third followed early in the second half.
Werner's role in Havertz's first-half goal also served as a reminder of why he is in the team. His driving run after a defensive error could well have seen him score himself, but instead bounced off the post - the third time he hit the woodwork in the first half - and into Havertz's path.
A chance to rest before Madrid
Another benefit of the scoreline came at the break. Chelsea were so far out of sight that they were able to withdraw Kai Havertz at half-time and wrap him in cotton wool, while the same happened with Thiago Silva and Mason Mount shortly after the hour mark.
Tuchel admitted the Blues would suffer European elimination if they put in another performance like the one against Real Madrid at Stamford Bridge. However, there may now be the faintest glimmer of hope.
With the Spanish side in action on Saturday night, Chelsea have a bit more preparation going into Tuesday's clash at the Bernabeu. However, the chance to keep Havertz, Mount and Silva well-rested could prove even more important if they are to stand a chance.
Nightmare for Romeu against his former club
Despite failing to establish himself at Chelsea, Oriol Romeu has developed into an accomplished Premier League midfielder. There was little of that quality on show against his old employers, though.
The Spaniard has more than 200 top-flight appearances under his belt, the bulk of them for Southampton. However, he was withdrawn by manager Ralph Hasenhuttl before half-time with the hosts already 4-0 down.
Romeu wasn't the only one to have a poor day at the office. However, it may well have hurt more considering the opposition.
Christensen on the right again
Thomas Tuchel admitted he made a tactical error with his use of Andreas Christensen against Real Madrid, leaving the Dane exposed up against Vinicius Jr. However, rather than bringing in Reece James, the manager kept Christensen in a similar role at St Mary's.
Admittedly, Mohamed Elyounoussi isn't quite the same calibre of player as Madrid's Brazilian star, but it will have been a confidence boost for the Chelsea man after his midweek woes. Sometimes immersion is the best way for a player to shake off a difficult night.
Christensen was pushed inside for the final half hour, with James getting a run-out from the bench. However, it will be interesting to see how Tuchel sets up during the week.
