Antonio Conte could've made something up when asked why David Luiz was left out of his squad for Sunday's game against Manchester United. A slight knock, perhaps. Or maybe a personal issue. Instead the Chelsea boss went with a brutal approach.

“It's a tactical decision, only a tactical decision,” the Italian explained bluntly. “I must take the best decision for the club, not for a single player. It’s only a tactical decision. It’s normal.”

In truth dropping a man who was vital to Chelsea's Premier League title victory last season is anything but normal, and Conte would've known that. Luiz played through the pain last season for the Blues, he was the rock the back three was built on.

But cross Conte once and you're in trouble. Luiz's good friend Diego Costa discovered that in the summer and now the floppy-haired Brazilian has suffered the same fate.

Make no mistake about it, Luiz may have sat in the stands for Chelsea's win over United but he had, essentially, been placed on the naughty step by Conte. There have been several stories written as to why, ranging from the defender questioning Conte's tactics to his close friendship with Costa.

You sense the latter is more likely to be true, especially as it was meant to have occurred after the Blues mauling at the hands of Roma in the Champions League last week.

Either way, Luiz has been booted out of Conte's plans and faces a fight to save his Chelsea career.

“I don’t know,” Conte said when asked about Luiz's future. “He has to work really hard, otherwise they are on the bench or in the stand.

“This can happen to every one of my players, if I see they are not in good form. It’s normal. I repeat: I have to put my face to every situation and then sometimes to make important decisions.”

Conte has made his move, Luiz must now decide how he wants to play his hand. The Brazil international is, by all accounts, a well-liked member of the Chelsea side and his relaxed demeanour around the Cobham training ground is appreciated by the staff.

But his attempt to undermine Conte in front of the squad can't be tolerated, by the Italian or the club. So either he gets on board or is moved on in January. Unfortunately Luiz must be made an example.

For too long Chelsea managers have been at the mercy of their players; if they stop performing, which has happened far too often, then the man in charge is given the boot.

It is a fate José Mourinho suffered, and before him André Villas Boas and Carlo Ancelotti.

Admittedly, it was different for the trio above. Over the last decade the Chelsea dressing room contained club legends – such as John Terry, Frank Lampard, Petr Cech and Didier Drogba – while the likes of Ashley Cole, Ricardo Carvalho and Michael Ballack were all big personalities.

Trying to take on those players would've – and in case of Villas Boas did – end in disaster. But Chelsea's dressing room is no longer as powerful and it's the perfect opportunity for the club to back their manager and break a pattern that has repeated over the last decade.

Michael Emenalo's resignation as technical director is a blow in achieving this. He may not have been particularly popular with Chelsea fans but he was a big advocate in the Blues hiring Conte and he remained a supporter of the Italian.

Marina Granovskaia will take over Emenalo's responsibilities until a replacement is found, which could prove costly in Conte's bid to assert his authority over the squad.

The two have been at loggerheads since the summer, with their relationship deteriorating over the club's sluggish movement in the transfer market.

Granovskaia is Roman Abramovich's closest aide at Chelsea and will be deemed far less expendable than Conte, but it's vital she and the rest of the Blues hierarchy see the opportunity that has presented itself over the past week.

It's a chance to show the squad that nobody is bigger than the manager, no matter their status, wage or whether they were players wanted by Abramovich, as in the case of Luiz, rather than the man in charge of the side.

It may be painful and it could see Luiz moved on at a loss, but in the long run it could prove an invaluable decision. Take on the manager and suffer the consequences is the message that needs to be sent out and understood.

For too long Chelsea have pandered to their stars and, while there is no disputing it's paid off to the extent that trophies have been collected regularly, it isn't sustainable for years to come.

The pool of elite coaches isn't huge, it's why Chelsea turned to Mourinho once again back in 2014, a little under seven years after he left the club. The Blues were running out of viable options.

And if Conte goes – and the indications are he will leave at the end of the season no matter what – then whoever the Blues turn to next has to come in knowing they're in a stronger position than than the players they're managing.

This could be a turning point for Chelsea and it's one they can't afford to waste.

Premier League