Ron Vlaar and Darren Bent will both miss the Liverpool game on Saturday.
Vlaar is undergoing a scan today to ascertain the severity of his calf problem.
Paul Lambert says he'll definitely be out at Anfield but is hopeful the issue isn't too serious.
Bent had a scan earlier this week and it showed a pull in his hamstring, which will keep the striker out for a "few weeks."
Gabby Agbonlahor is also a doubt for the clash on Merseyside but, in good news, Joe Bennett and Enda Stevens are fit again.
Lambert said: "Ron is struggling with a calf. It's a blow. He's away for a scan now. It's not too far away but this weekend is too early.
"Darren is not fit. He's hurt his hamstring as everyone saw on Tuesday.
"He will be out for a few weeks. It was scanned on Wednesday. It's come up there that he's pulled his hamstring. I think he will be about for a few weeks.
"We will also have to see how Gabby is. I know he was on the bench on Tuesday. But he had a little problem the other night.
"But the others don't seem to be too bad. Enda is coming back. Joe is coming back."
Make sure you back the boys against Tottenham.