John Terry has reacted to Chelsea's worst run of form in the Premier League for virtually a generation by calling on his team-mates to "stand up and take responsibility".

The centre-half, who is recovering from a knee ligament injury sustained in last month's draw against Liverpool on his return from a domestic four-game ban, used his programme notes for Wednesday evening's final Champions League group game against Nordsjaelland to express his frustration at Chelsea's slump.

The team have not won in seven league games and face dropping into the Europa League, with that run having cost Roberto Di Matteo his job.

"Let's not beat around the bush: no wins in six games is simply not good enough and since I have been here I have not experienced a run like this," wrote Terry. "We, as players, have to stand up and take responsibility – stand up and stay together. We demand a lot of ourselves and we have to focus on rediscovering the winning habit."

The former England captain will be assessed by Chelsea's medical staff on Thursday to determine whether he will travel with Rafael Benítez's squad to Japan for the Fifa Club World Cup. The player had been hoping to play some part in training this week but the club are anxious to be sure he can twist without discomfort on the joint before contemplating his return to first-team action.

In the meantime he has been forced to watch on as his side's campaign unravels, with the defeat by West Ham at Upton Park at the weekend clearly having tested his patience. "The game on Saturday was hard for me to watch, especially after we had played so well in the first half," he wrote. "We could have been out of sight by half-time with the chances we were creating and the way we were dominating the game.

"West Ham came out for the second half strongly and we didn't respond. We need to be stronger than that and we know we can't let that happen again. Let's show some fight and desire for our club and for the shirt. Players will come and go, but what must always remain is the spirit within this club: never give up and fight for every last thing."

The Chelsea midfielder Mikel John Obi has signed a new five-year contract at the club that will extend his stay at Stamford Bridge through to 2017. "Being 25 I think I am now hitting my peak but, as a player, you want to improve every day and there is still room for that," said Mikel, who joined in the summer of 2006 from Lyn Oslo in a move that was contested by Manchester United. "I want to learn from the players and the manager and I just want to keep going."