It's the moment that's been looming since September.
Having accumulated four yellows in the first six Premier League matches, it's remarkable how Diego Costa showed the restraint to go another 11 before picking-up his fifth.
That it coincided with N'Golo Kante's own fifth, on Saturday at Crystal Palace, is bad luck for Blues – as both will now be out of the Boxing Day clash at home to Bournemouth.
That leaves Conte without probably his two most important players, and with big questions about the fill-ins.
The Italian has worked with a very small group of players as Chelsea built an impressive lead at the top of the table.
A settled XI has been tinkered with by necessity, with Willian stepping in for Pedro out wide, and Cesc Fabregas playing an occasional starring role in the midfield.
The question is how will Conte deal with it?
The first switch is an easy one to call: with Michy Batshuayi pretty much a dead cert to deputise for Costa.
Speaking after the Palace win (see above in video), Conte was clear the Belgian had a way to go before adapting to the Premier League.
The manager is too astute to highlight his players' weaknesses in public, but was clear the physical demands of football in England were a challenge for the 23-year-old.
That is an issue that won't be resolved inside a week, of course, with Batshuayi being seen as a medium-term club project.
Though he undoubtedly has enough raw talent to mix things up for Bournemouth at the back, and many will relish the chance to see him given rare exposure.
Dominic Solanke will surely be called-up to the bench.
The replacement of Kante is far more challenging a prospect: for he is truly one of a kind, and it has to be doubted whether any player can truly replicate what he brings to a side.
His removal immediately chips away at Chelsea's apparent invincibility: the former Leicester man has the greatest career win percentage of any player presently in the Premier League.
Cesc Fabregas, the first name that springs to mind as replacement but couldn't be a more different player.
He will offer more direct attacking options.
However, Bournemouth don't travel well: they have won only one of eight matches on the road this campaign – last month at Stoke.
And there have been calls for Chelsea to be more ambitious in the way they are set-up at home against lesser sides.
A few weeks ago there was another name that may have been dropped into the mix: that of Oscar.
But with his move to China all but finalised, that seems highly unlikely now.
Both Mikel John Obi (who is a minor doubt with a muscular injury) and Ruben Loftus-Cheek are out of favour with Conte – and both are being linked with possible January loan moves.
Nathaniel Chalobah might be as close to like-for-like as Chelsea can find – but only Conte will know if he is ready for 90 Premier League minutes in that role.
There is also the prospect of playing Pedro wide, with Willian in the middle: though he probably offers less direct forward options there than Fabregas, with not a lot more defensive stability than the Spaniard.
There's one slightly off the wall suggestion too: that of playing David Luiz as a defensive midfielder.
There's certainly merit in it: though the biggest failing in the plan may lie in who replaces him in defence.
While many would want to see Kurt Zouma there, it is still quite early in his recovery to hand him so much responsibility from the off.
John Terry remains an injury doubt; while playing Branislav Ivanovic on the right, with Gary Cahill in the middle, adds vulnerability while removing much of the ability to build fro the back.
It is a tough choice. But, as has been pointed out numerous times, you will know the quality of a manager by the decisions he takes when difficulty strikes.
