The 51-year-old Chelsea manager was left frustrated and disappointed at the end of his 100th match in charge of the club after his side lost 1-0 at home to Manchester United in the first leg of their quarter-final.
They now face a huge task at Old Trafford in the second leg after Wayne Rooney's first half winner.
Although not yet out of the tie, their hopes of advancing to the semi-finals for the sixth time in eight seasons are slim, and so are Ancelotti's prospects of remaining at Stamford Bridge for next season.
Chelsea's billionaire owner Roman Abramovich covets the Champions League more than any other trophy and has shown little mercy to the men who have failed to deliver it.
Since buying Chelsea in 2003, Claudio Ranieri, Jose Mourinho, Avram Grant, Luiz Felipe Scolari have all tried and failed to make Chelsea champions of Europe.
Guus Hiddink, who took charge of the club on a caretaker basis after Scolari left in the middle of the 2008/09 season was also unable to win it, so Abramovich turned to Ancelotti, one of only six men to lift the European Cup as both a player and coach.
Ancelotti guided Milan to Champions League triumphs in 2003 and 2007 as well as losing the final to Liverpool in 2005, so certainly has the experience and ability to complete the job.
His first season in London last season saw Chelsea win the FA Cup and League double for the first time, but after a fantastic start to this season, they have stumbled, out of both the FA Cup and effectively the title race where they trail United by 11 points.
TORRES FLOP
The addition of Fernando Torres to the side for a British record fee of 50 million pounds in January was supposed to provide the spark for another assault on the title, but Torres, despite Ancelotti's continued support, has failed to score a goal in nine appearances.
Ancelotti kept faith in the Spaniard for the duration of Wednesday's defeat, even keeping him on and substituting Didier Drogba for Nicolas Anelka in the closing stages.
But Torres only real contribution was a header saved by Edwin van der Sar late in the game and a booking for diving.
Ancelotti though was unable to hide his frustration with the officials after they turned down what looked a certain Chelsea penalty after Patrice Evra clattered into Chelsea midfield Ramires in stoppage-time.
"It was a clear penalty and everyone knows it," the Italian told reporters. "The problem was that it came in the last minute and sometimes its not easy for the referee to give a penalty in the last minute of the game.
"I'm disappointed, but this is the result, it's past."
"Now we must go to Old Trafford and save the tie. We have confidence to do it. Last year it was the same -- we had to win at Old Trafford and we did this."
