Didier Drogba has admitted the Chelsea dressing room has been an "unhappy" place during their recent slump in form and says his own performances have been hampered by his battles with injury and malaria.
Both Chelsea and their Ivorian forward have been some way short of their best since a promising start to the season, with the Blues recording just one win in nine and Drogba contributing only eight goals in all competitions.
His fitness problems have been well documented, not least the bout of malaria which was diagnosed in November.
Drogba told The Sun: "Injuries and the malaria have damaged my performances. I am still not 100% but I am fighting in each match to improve my playing levels and help the team.
"This season has been complicated for me by physical problems.
"It has not been easy to regain my strength but we need the points and my presence is necessary. I have always sacrificed for the team - and Chelsea need me."
As for the team's struggles, during which they have slipped from pace-setters to outside the Champions League spots, the 32-year-old added: "Chelsea's current position compared to last season is actually very similar but maybe our injuries and less goals have brought about a negative mood.
"In the last weeks Carlo Ancelotti has been unhappy - and the squad, too. Chelsea are not accustomed to defeats and the dressing room has suffered.
"But the season is long and it is normal to suffer lots of changes."