Peterborough United defender Craig Morgan will not be taking his starting place for granted ahead of the new Championship season.
Morgan returned to action in Saturday's 3-0 win over Oxford after a spell out with an ankle injury.
He told BBC Radio Cambridgeshire: "Nobody knows what the gaffer will go with so nobody is certain of a place.
"I don't suppose we will know the starting XI for Derby until the Friday before the game."
The former MK Dons player lined up alongside Gabby Zakuani at centre-back against Oxford with boss Darren Ferguson naming a strong starting line-up.
He spent the second half of last season stuck on the sidelines with a toe injury, but is confident he won't feel the effects of his latest knock.
"I turned my ankle in training last week, but it's a lot better now after a week of treatment," he said.
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"You never want to get injured, especially a week or two before the season starts, but I should be ready for Derby."
Tommy Rowe, Shaun Batt and Aaron Mclean grabbed the goals as Posh ran out comfortable winners at the Kassam stadium.
Meanwhile, striker Craig Mackail-Smith was once again absent, leaving him very unlikely to start against Derby on Saturday.
He has been struggling with body alignment issues and is yet to kick a ball in pre-season.
Posh play their final friendly at home to Sunderland on Tuesday.
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