Di Matteo revealed for the first time his darkest fears after the Blues' fateful Barclays Premier League defeat at West Brom on March 3, which led to Andre Villas-Boas's demise as manager less than 24 hours later.
Villas-Boas's then-assistant was immediately appointed caretaker following a training-ground meeting with owner Roman Abramovich, chairman Bruce Buck and chief executive Ron Gourlay.
But that was far from the outcome Di Matteo was bracing himself for when he was summoned by his bosses.
Asked if he had been expecting the boot, he said: "I did, yeah, quite frankly. It was a very emotional day, that day, for us."
Remarkably, Di Matteo's revelation came as he marked 257 days in charge, the exact number of days Villas-Boas had spent in the hotseat.
Even more remarkably, it came the day before Chelsea's first trip to The Hawthorns since last season's defeat and Di Matteo's first return there as a manager since West Brom sacked him just over a year earlier.
Having masterminded the greatest climax to a season in Chelsea's history, a loss pn Saturday would not spell the end of Di Matteo's time in charge at Stamford Bridge.
But a fourth straight league game without a win would certainly see the vultures begin to circle at a time of year when Chelsea traditionally struggle.
Pointing out they had won matches in both the Champions League and Capital One Cup during the period they had dropped from first to third place, Di Matteo said: "You need to put things into perspective.
"We're in good shape, the players are in good spirit. We need to keep going on and try to get the win.
"We've shown our character many, many times. It's not just a test of character.
"When we play well and manage to do so in a game, we can win games."
It is easy to imagine Di Matteo having given his bosses at West Brom the same assurances before he was unceremoniously sacked last year.
The Italian lost his job after a lengthy run of bad results, although he had just led them back into the Premier League at the first attempt and they were not even in the relegation zone.
However, replacement Roy Hodgson did turn their campaign around - ultimately earning him the England job - while Di Matteo's subsequent adventures are now the stuff of legend.
Astonishing Champions League and FA Cup triumphs last season led to him being appointed Chelsea manager full time and gave him licence to be philosophical about his Hawthorns demise.
Insisting his sacking did not dent that self-belief, he said: "I learned a lot of things - which people to trust, who not to trust.
"I'm certainly a better coach and manager now from the experience I had in the past, and the experience I had here as an assistant and now a manager working with these players."
Di Matteo insisted he bore no grudges over his controversial dismissal in February 2011, which ended up working out spectacularly well for both parties.
Former Chelsea team-mate and assistant manager Steve Clarke has led the Baggies to fifth in the table this season and Di Matteo said: "I'm pleased for him."
Asked if he could have done the same, he replied: "God knows."
But he added: "They certainly have a stronger team. They have made some good signings, and are more established now as a Premier League club."
There are still plenty of players there from the Di Matteo era and after reeling off a list of names, the Italian said: "I'm not taking credit for them, but there's still a good number from when I was there."
West Brom's home record is second only to Manchester City's and they may fancy their chances against a Chelsea side who saw several of their players forced to travel long distances to play for their countries in midweek.
Di Matteo hit out at November's midweek friendlies, saying: "From a club point of view, they don't make any sense.
"Most managers won't be too happy having three-quarters of their team jetting around the world for a friendly."