N'Golo Kante of all people gave Chelsea the lead after the half hour, before new signing Jorginho scored one of the collest penalties you'll ever see to double their advantage on the stroke of half time.
Pedro completed the scoreline ten minutes from the end in a comfortable win for the Blues and a worrying start for the Terriers, who struggled to score last season and could suffer the same problems this time around.
"I'm very happy because in the first part of the season for us it won't be easy for us to gain points," said Sarri. "The first half was hard. If you look at the result you think it was an easy game but in the first half we were in trouble for 15 minutes against a physical team, we are not a physical team. In the second half the opponent was a bit tired and it was easier.
"We have to improve to defend in the other half, to press, especially against three defenders. We have to move the ball faster. In the first half we didn't, it was better in the second but we had more space and time.
"It was really hard for us because they played all their pre-season matches with a 4-2-3-1, only one match in a 4-3-3. We have never played against 3-5-1-1 and we weren't ready. It was a problem. Maybe for Napoli last year it wasn't a problem but for Chelsea, with only three days training together, it's clear it was a problem."