Chelsea manager Antonio Conte says he deployed the 3-4-3 formation against Hull City after being convinced by what he saw in training.
The Blues kept a rare clean sheet this season as they battled past Mike Phelan's side at the KCOM Stadium.
They will resume the domestic league with two home games after the international break against Leicester City and Manchester United.
"It's fantastic for him [Diego Costa] and for us that he's scored six goals," Conte said.
"Diego has the opportunities in every game but what's important is the work he does for the team, together with Willian and Hazard.
"When you work hard you usually get opportunities. I'm pleased for him, Willian and Hazard. Hazard played well, with the right intensity and tried to do what I wanted.
"It can be a big change in the tactical aspect. More than the system, what's important is the principles, then you can change. This week we've worked a lot, we must find the right way to be more compact.
"A clean sheet is important for the confidence. We are working very hard and we must continue in this way.
"Chelsea is a great team and I try to choose the best team because I want to win, the club and fans want to win. We have different options, that's normal. Together we win, together we lose."