"At the start of the season we probably had five or six players ahead of Paul Ritchie so he couldn't get games," Keegan told the club's official site.
"We loaned him to Portsmouth for three months and he won't come back until that time is up at Christmas and we insisted on that."
"We have just been hit in that area but even playing with three at the back we have the cover.
Jihai Sun who had moved to right wing back can play in the back three, Gerard Wiekens did well on Tuesday night as did Richard Dunne."