McKenzie picked up a dead leg against Wolves and scored the winning goal before he had to be replaced but is now rated as highly doubtful.
"Leon is a big doubt, unfortunately," said City boss Chris Coleman to the CT. "He has got a haematoma in his thigh and it is not really settling so he has not been able to train all week. "We have got eight games coming up in the next month and we have got to make sure we get him back as quickly as we can.
Although off form, Freddie Eastwood may have to replace him but Coleman said: "Freddy Eastwood has got a really bad knee and could hardly walk on Wednesday but he had a light session yesterday and we will see how he reacts today."
Aron Gunnarsson is available again after a two game ban, Jordan Henderson is allowed to play by Sunderland but City have not yet had permission from Chelsea to play Lee Sawyer.
Stephen Wright is suspended and David Bell is cup-tied.
Chris Coleman is not expected to announce his team until the day of the game saying: "I haven't made my mind up yet."
More can be seen here
http://www.setanta.com//uk/Videos/football/2009/02/13/Coleman-reveals-selection-headache-video/