Aston Villa manager Tim Sherwood is worried about Adama Traore's injury and warned the Spaniard he was now a "marked man".
The 19-year-old former Barcelona man's home debut for Villa included a goal in his side's 5-3 extra-time win over Notts County in the League Cup on Tuesday.
"The negative is that Adama got injured. The only way to stop him at the minute is to kick him. He's a marked man. He will have to get used to it," Sherwood said.
"It doesn't looked good to be honest. He took a heavy knock - I thought it was a bad tackle. It was his ankle.
"He's a real talent. It's too soon to tell how serious but he's packed in ice and hobbling around."
Sherwood said the derby was reward for the fans.
"I have never been involved in that game," he said.
"Obviously I know now - two minutes after the teams were drawn out together - how important it is.
"If the fans stick with us like they did tonight, we will give them something to shout about. We owe it to them. The reason we're playing Birmingham is because of what they did tonight.
"We will give them a performance. We won't leave anything on the field."
