The Italian was left "shocked and surprised" as Chelsea imploded either side of half-time to lose 3-1 against Arsenal - a defeat that left them fourth, six points behind league leaders Manchester United who have a game in hand.
No wins in their last six league matches and a meagre haul of six points from 24 which is more in keeping with a side heading for relegation has left Chelsea facing the very real prospect of beginning the New Year outside the top four.
It also raises the possibility that Chelsea's Russian owner Roman Abramovich, not best known for his patience, could dispense with a manager who six months ago was celebrating the double at the end of his first season in charge.
Wednesday's home game against Bolton Wanderers has now become the proverbial "must win" for the Italian who said he was confident he would remain in charge.
"We have to wake up quickly," Ancelotti, well-used to the hiring and firing mentality of Serie A, told reporters as he came to terms with Chelsea's fifth loss of a season that began in a blaze of goals. "Maybe I need to be the first to wake up."
"I'm worried obviously. It's six or seven games that we haven't won and I haven't seen the team play how we want. We have had difficulty to play our football and so this my worry."
More worrying was that, apart from the injured Nicolas Anelka, Ancelotti fielded a pretty much full-strength side with Frank Lampard starting for the first time since August.
Chelsea, however, offered little threat with Lampard, Florent Malouda, Didier Drogba and Michael Essien virtually anonymous.
When Theo Walcott added to goals by Alex Song and Cesc Fabregas to make it 3-0 in the 54th minute Ancelotti, who cut an isolated figure in the technical area for the entire 90 minutes, wore a bemused expression as a team of double winners crumbled in front of his eyes.
"I've had a very good feeling with my players in the past two weeks and I didn't expect this," said Ancelotti, who thought his misfiring side had turned the corner in a 1-1 draw at Tottenham Hotspur 15 days ago before the big freeze.
"I'm surprised by this performance. I had hoped that the bad moment was over. We worked very well in the two weeks but it was not enough. We didn't play well in this game."
With Chelsea's bench containing several inexperienced players such as Gael Kakuta and Josh McEachran, it is clear that reinforcements are needed urgently if Chelsea are to revive their flagging season.
Asked whether he will get the chance to spend Abramovich's money in the transfer window, Ancelotti was said that decision was not up to him.
"I can't use any new players on Wednesday at Bolton that's for sure," he said. "When the market opens I can answer that.
"We are sleeping, this is the reality. If you play against a good team like Arsenal you can't win if you don't wake up.
"I think (Abramovich) will not be happy but I take my responsibility. This is not a question you can ask me about how long he will be a patient. Obviously we have to do better because he's n
