Manchester City boss Roberto Mancini says defender Dedryck Boyata could keep his place against Manchester United.
The Belgium Under-21 international was handed a surprise debut against Middlesbrough in the FA Cup due to a spate of absentees.
With Nedum Onuoha, Joleon Lescott and Wayne Bridge injured and Kolo Toure on international duty, Mancini is short of experienced defenders.
England international Micah Richards could be fit after limping out of their 1-0 win at the Riverside, although the Italian boss says Boyata is a realistic option.
"It's possible he could play because we have a lot of problems in defence," explained Mancini.
"He and the other young players played very well in Middlesbrough."
Richards would likely partner Vincent Kompany at the heart of City's defence for their Carling Cup semi-final first leg against their arch-rivals if Boyata misses out.
Winger Shaun Wright-Phillips and striker Roque Santa Cruz are also touch and go for the first leg at Eastlands on Wednesday and Mancini says he will not gamble on their long-term fitness.
"We will see how Shaun is and we aren't certain on Roque," he continued. "We don't want to take a risk."