Carlo Ancelotti believes a disrupted start to the new season could harm Chelsea's chances of successfully defending their Premier League title.
The champions begin the new season at home to newly-promoted West Bromwich Albion on Saturday August 14 but will do so without a host of players who have been involved in the action at the World Cup.
The Blues returned to pre-season training on Monday but the likes of England World Cup trio John Terry, Frank Lampard and Ashley Cole, Ivory Coast pair Didier Drogba and Salomon Kalou, Portugal duo Deco and Paulo Ferreira plus Serbia's Branislav Ivanovic, have all been granted additional time off following their exploits in South Africa.
"It could be a little different this year, a little difficult because we don't have all the players to start the season but we can still do a good job," Ancelotti told the club's official website.
Speaking about the return to pre-season training, the Italian coach added:"Last year we started at the same time and we need maybe five weeks to prepare the team, to do the best physical preparation.
"We will have the other players on July 22 and 26, but for the first games of pre-season they will not be involved."