John Terry could miss Chelsea's entire festive fixture programme after Rafael Benitez admitted Friday his recovery from knee surgery was proving more problematic than first thought.

Interim manager Benitez was hopeful Terry would be fit to return for one of the Blues' four matches over Christmas and the new year.

But he stressed that he could not "guarantee" that, adding of his captain's recovery: "It's one step forward, one step back."

Benitez confirmed Terry, who had been scheduled to return almost two weeks ago, would definitely miss Sunday's Premier League game against Aston Villa.

Terry trained without the ball today but was still not ready to return to full-contact exercises, with Benitez revealing the defender was prone to an adverse reaction 24 hours after training.

"The knee is quite complicated," he said. "At least he's now on the pitch -- that is positive news -- but we cannot say, we cannot predict how long it will take."

Asked if Terry would make his comeback in the next fortnight, Benitez said: "I hope so but I am not a doctor. "So I cannot guarantee anything."

Benitez was confident Terry would not require further surgery and would not be drawn on reports the 32-year-old was close to opening talks on a new contract to replace the one that expires in 18 months.

Pressed on Terry's importance to Chelsea -- there is a huge difference in their win-loss record with and without their skipper -- Benitez said: "If he's the captain, it's because he's a player that can be a leader.

"I have seen he has a great character."