#5 Easing things down helped Chelsea keep their lead

Thrice in the space of eight games, Chelsea have been bound for the restart with a lead. However, only on one out of the three occasions prior to this victory, the Pensioners ended up bagging all three points.
A lead against Leicester City was blown away before a two-goal advantage against Sheffield United at home was surrendered. Teams began to understand Chelsea's brand of football, but here, they just applied themselves a bit more in possession which calmed their nerves down.
They knocked the ball about from corner to corner in a conservative fashion, which ultimately paid off as Southampton were made to work harder. It was a far more mature performance, indeed.
And they capped off that brilliant piece of tactical play in the second half with an excellently worked goal for Michy Batshuayi, who played a gorgeous one-two with fellow substitute Christian Pulisic to tuck home the fourth.
Following their 4-0 drubbing away from home against Manchester United, Chelsea have netted a total of 12 goals in three subsequent away games and taken nine points. Some way to respond.