He knew what he was doing then, Antonio Conte.
Knew what he was doing when he left Eden Hazard and Diego Costa kicking their heels for an hour on a Wembley bench.
They came on to change the course of Chelsea’s FA Cup fortunes, they went on to take Chelsea a step closer to the Premier League title.
Hazard scored the first and Costa the third and fourth after Gary Cahill had nudged Chelsea back ahead following Oriol Romeu’s equaliser.
Quite simply, Hazard and Costa were the nerve-settlers. Make no mistake, there were nerves here against a Southampton side who did not roll over.
Fears that the Saints would be strolling rather than marching were hardly allayed by the resistance to Chelsea’s first goal. To call it token would be gross flattery.
It was a cute pass from Cesc Fabregas to Costa, but the time and space afforded was inexcusable.
Seven Southampton players studded the penalty area but Costa simply rolled a routine ball to his only available colleague and Fraser Forster was bawling at his lounging defenders before Hazard’s strike had disturbed his net.
As more midfield freedom followed for Chelsea, you could imagine the knowing looks in North London but if if there was a casual approach to Saints’ grittier duties, there was a pleasingly carefree approach to the more glamorous duties.
That is why Claude Puel’s purists were always a threat.
Their crisp-passing patterns had already produced a couple of half-decent opportunities before parity arrived via an abjectly-defended set-piece.
After a corner kissed Cesar Azpilicueta’s crown, Manolo Gabbiadini, having skulked beyond right far post, drilled in a low strike that, after rebounding off the legs of Thibaut Courtois, gave Romeu a hurried tap-in.
Courtois was not culpable but there was a general anxiety about hiswork that symbolised uncharacteristic uncertainty tainting Chelsea’s defence.
Ironic, then, that it was one of those nervy defenders who gave Chelsea a half-time lead.
Kante had hardly been in imperious Player of the Year form but his standard cross produced undue panic and when Marcos Alonso headed it laterally, Cahill nodded it emphatically.
It might not have been an ill-deserved advantage but it had not been an overly convincing half of Chelsea football. However, the manner of Cahill’s goal was an illustration of the sluggishness of some Southampton defending.
Their Premier League lives did not depend on this and they defended accordingly. That is why Hazard and Fabregas were allowed to have a little knockabout from a corner with the latter’s chip landed on Costa’s unmistakable head.
Somehow, Costa only had Ryan Bertrand in anything like close attendance and did not have to get airborne to put clean air between the two teams.
The acclaim that followed was familiar yet this performance summed up this curious individual.
Cumbersome? Tick. Comparatively slow? Tick. Always looking for a ruck? Tick. Wears the facial look of a guy that fancies a move? Tick.
Somehow finds a way to score? Tick. Effective? Tick. Always causing problems? Tick. Absolutely fundamental to the success of this team? Tick.
He was ending a mini-drought here – his first goal since early March – but that is 51 in 85 Premier League appearances and only seven players have reached the half-century landmark faster.
There remains a feeling that he could yet depart in the summer and his unique blend will be hard to replace.
If he does go, he will surely leave a champion.
While Chelsea saw this out with some confidence, there is still work to do but their main men show few signs of waning.
John Terry got a run-out to great delight but the main men were already out there.
As if anyone needed reminding, Diego, with a little help from Eden, capped matters with a stunning sensational effort, rendering Bertrand’s late headed goal irrelevant.
The main men, Hazard and Costa, have brought glory a step closer.