Cech says it's "the most important part of the year".
"Pre-season is the most important part of the year," says the goalkeeper to chelseafc.com. "It's where you make the base for the season ahead, and you need to be ready from day one. You can't do it again during the season, it's too late.
"You have to get the squad gelled and in the best condition possible when the season starts. During the season the match fitness grows but your physical state is simply maintained from the start of pre-season.
"'It's also the time when the team is together for the longest time, everybody is there and you have time to get to know any new people. The new manager can get to know people and work with them over those few weeks, so it's where you create a team."