Then, with 14 minutes remaining, Sarri sent on the man who remains the towering talent in Chelsea's side, if not in stature, Eden Hazard, the architect of the third goal for Pedro.
Hazard is not yet fully fit, but then when you are as good as him, that does not matter, and a tiring Huddersfield did not know whether to tackle, back off or just simply admire this mesmerising little man.
When Huddersfield manager David Wagner was asked how he felt, at 2-0 down, seeing one of the world's best footballers come off the bench, he simply laughed.
"Yeah, he's good, isn't he? Everybody fights with his weapons. They have Hazard and we have passion, desire and togetherness. Sometimes mentality can beat quality. This time the quality was too big, even though the mentality was there."
Sarri looked relieved after this first league victory, although he was bemused at Wagner's 3-5-1-1 formation, claiming that it was the first time they had played it, as if to make the point that he had done his research.
"In the first half, we were in trouble," he said. "For 15 minutes against a very physical team, you saw we are not a physical team. The best of the game was our capacity to suffer for those 15 minutes, and in the second half, when the opponent was a bit tired, it was easier."
The Chelsea manager said his first experience of English league football had been revealing, especially when it came to referee Chris Kavanagh, whose fourth official Michael Oliver he spent much of the game interrogating over decisions.
"From the referee point of view, it's really different," he said. "[Yesterday], with an Italian referee, there would be a lot more fouls."
The question is how long it will take Sarri to weave the magic he created at Napoli.
"I have to know the characteristics of the players," he said. "I don't want to do another Napoli. I want to do a good Chelsea."
This was a tough start for Wagner's team, behind to Kante's goal after 34 minutes, which the Huddersfield manager thought took a deflection. The home fans focused their anger on referee Kavanagh, in particular for his decision to award that penalty Jorginho dinked in for Christopher Schindler's foul on Marcos Alonso, the point at which the game was out of Huddersfield's reach.
Hamer and substitute Adama Diakhaby were the only debutants in Wagner's team, with Alex Pritchard playing off Steve Mounie, the Englishman replaced at halftime with the more physical Laurent Depoitre.
In defence for Chelsea, David Luiz, something of a catastrophe in the Community Shield six days earlier, was authoritative, and he needed to be in those opening stages.
Wagner's team pressed high, their five-man midfield engulfing Chelsea's midfielders at times - even with their precise passers.
Nevertheless, Chelsea were "clinical", Wagner noted, three of their four attempts on target resulting in goals.
The first came when Jorginho released Pedro in midfield with a deft flick and the Spanish winger set off towards the left side where he found Willian.
The Brazilian looked on another level when he had the ball and he picked out Kante, whose shot was struck into the ground and bounced up past Hamer.
Mounie hit the bar with a header from a corner but that was as close as Huddersfield came to a goal.
Wagner said his side was "in shock" at the start of the second half and that might explain how slow they were to come into it.
Enter Hazard. A surging run from inside his own half had Huddersfield in confusion and, using Alvaro Morata as a decoy, Hazard slipped the ball right for Pedro to score the third.
Against the league's best sides, Chelsea, in this time of transition, will need Hazard to be as good as he was at the World Cup. If he plays the same way against teams like Huddersfield, there will be no stopping him.
