The third-round encounter at Old Trafford provides an opportunity to bounce back from the disappointing 1-0 reverse to Wolves in the Premier League as the Reds begin the road to Wembley against top-flight opponents.
Ralf has suggested he will not make wholesale changes to the line-up, as some other clubs do at this stage of the competition.
"We will definitely not play with eight or nine different players," the boss told MUTV's Stewart Gardner. "Or even 10, as we did against Young Boys in the Champions League.
"We will try to play with the best possible team, with a strong team.