Chelsea will wait anxiously for the result of scans on Michael Essien's damaged hamstring today amid fears the midfielder could be out for some time.
Essien is already out of Saturday's home clash with Everton after limping off midway through the first half of last night's 2-2 draw with APOEL in his side's final Champions League game at Stamford Bridge.
The Ghana midfielder had hauled the Blues level in the 18th minute before breaking down in the centre of the pitch moments later.
The club will assess the extent of the injury today but if Essien has torn the hamstring, he could be out for as long as six weeks - throwing his participation in January's African Nations Cup into doubt.
"Michael has a problem with his leg," said Ancelotti. "We will look at him over the next few days and check on him.
"We hope it's not a big problem but he will not be able to play on Saturday."
Chelsea had already topped group D before last night's draw which once again threw the spotlight on Chelsea's defensive liabilities.
Goalkeeper Petr Cech was left out of the side after his free-kick blunder for Manchester City's winner on Saturday and Frank Lampard, who missed a penalty in the same defeat, started on the bench.
Sloppy defending from captain John Terry allowed Marcin Zewlakow to put APOEL in front in the sixth minute before Essien and Didier Drogba fired the Blues in front by half-time.
But a careless pass by John Mikel Obi allowed Nenad Mirosavljevic to grab an equaliser with four minutes left.
Ancelotti was unhappy with his players and added that the performance of 18-year-old Gael Kakuta, making his first start for the club, was the only highlight.
"This was not a good evening," said the Italian.
"We did well in the first half after going behind in six minutes.
"We were playing well and scored two goals. We played with intensity but then lost our concentration. For this I am not happy.
"We have to play for 90 minutes with intensity and concentration. It's a psychological thing.
"This was not how we want it. I spoke with my players about it afterwards.
"The first goal can happen, the second one no. It was the consequence of our soft play.
"We had the possibility to close the game out but didn't play well.
"Kakuta is the only one who could think he played well. He showed his talent and made a fantastic pass for the second goal."
APOEL coach Ivan Jovanovic was overjoyed after his Cypriot side upset Chelsea.
"This a very good evening for my team," he said.
"It's a very important result drawing with one of the top teams in Europe.
"In a game like tonight we knew we wouldn't have many chances and we've been lucky that we were able to score twice in five or six."Reuse content