"We are missing quite a few key members of the group," Jewell told the Derby Telegraph.
"It is really frustrating but I'm trying not to get frustrated and rush them back.
"You want to get them games before the season starts but you do not want them to aggravate the knocks or strains they have.
"Me and the physio are having a bit of argy-bargy at the moment.
"I want them playing and he wants that extra day or two for them."




