Reading boss Brian McDermott says he is not looking to sell any more players this summer but admits that Shane Long may still leave the club.
"I told Shane if a big club comes in I'll do right by him and try get him the right deal," he told BBC Berkshire.
"But if Shane goes that's it, there'll be no-one else. We already lost Mills and we got to keep this team together."
With Mills joining the Foxes earlier this month and Ivar Ingimarsson plus Zurab Khizanishvilli leaving the club in June, Reading have few options at centre-half.
Icelandic midfielder Brynjar Gunnarsson has stepped into that position during Reading's pre-season tour of Slovenia but McDermott admits this is only a short-term solution.
"I'm trying to find a centre-half because we need one, but having said that Gunnarsson has been outstanding there. Every time he's played there for us he's done well but it's not a long-term fix," he said.
Reading's last competitive match was a 4-2 defeat by Swansea in the Championship play-off final on 30 May, and McDermott insists the upset of failing to secure promotion has not affected his team after seeing them thrash NK Dravograd 7-0 in Putj on Friday.
"I was pleased. It was a perfect game for us really, as far as the first game back after last season goes," he said.
"Our work rate was very good and our attitude to the game was good so we're pleased with that, but we'll have a tougher test on Tuesday [against Turkish Premier League side Karabukspor].
"People said to me after what happened in May there'll be a hangover for the players but you can see there is no hangover, they are just ready to play now and looking forward to the season."