Didier Drogba feels Chelsea must "step up their game" if Carlo Ancelotti's men are to get their Barclays Premier League title defence off to a flying start.
Last season's Double winners went down 3-1 to Manchester United in the Community Shield at Wembley on Sunday, a fourth consecutive loss in their warm-up schedule. Ancelotti insists there is no major cause for concern as Chelsea build towards the visit of newly-promoted West Brom to Stamford Bridge this weekend.
"The game against United showed we are not ready. We have to step up our game if we want to start the season well like we did last year," said Drogba, who came on as a second-half substitute at Wembley and looked sharp as he continues recovery from a groin operation.
"A lot of players have only trained for 10 days. It is too short to be fit and ready for the big competition.
"We have to improve our game, even if we are not fit, and hope that in two to three weeks time we will be better.
"I hope it does not take that long but when you come back after a short holiday it takes a minimum of two to three weeks to have good preparation and be fit physically. I know I'm not ready yet."
Drogba - who played at the World Cup with a protective cast after fracturing his arm - continued: "Against United, we played without intensity, but we are working very hard in training trying to get fit early.
"It is not going to be easy but we need more time."