Had Mounie levelled with Huddersfield 1-0 down, rather than heading against the post after Mathias Jorgensen had flicked on Aaron Mooy's corner, perhaps Sarri's afternoon would have been far more uncomfortable. After a choppy opening half hour, N'Golo Kante made the breakthrough and, from that point on, there was only going to be one outcome.
FW Pedro, 8 - Linked up well with Azpilicueta in forward passages of play and was the main beneficiary when Hazard came on as he latched onto a pass from the Belgian global to smartly score the final goal.
The striker, who was the tournament's top scorer in Russian Federation, has now failed to score a Premier League goal in August at 14 attempts. "We did it better in the second half, there was more space and time".
FW Alvaro Morata, 7 - Led the line enthusiastically, held up the ball well when in possession and looked confident enough to suggest the goals that have been missing from his game will come soon enough if Sarri persists with him.
As Jorginho approaches the ball, he skips just before the taking his shot.
However, on the final day of England's summer transfer window, Chelsea confirmed the loan-signing of Mateo Kovacic from Real Madrid as part of the deal which saw Thibaut Courtois go the other way. He marked his Premier League debut with a very cheeky penalty past Ben Hamer to make it 2-0 at half-time.
"We were in trouble for 15 minutes against a physical team, we are not a physical team".
The Blues' new star in the midfield is Jorginho, who came over to Chelsea with Sarri from Napoli.
Huddersfield fans will have felt the half-time score was harsh, but Chelsea set about extending their lead after the restart. But things do look bright at the back for the Terriers.
It's a tricky start to the season, and after facing Cardiff on Matchday 3, Huddersfield then takes on Everton, Crystal Palace, Leicester, Tottenham, Burnley and Liverpool.