Derby manager Terry Westley is unsure whether to pursue his interest in MSV Duisburg striker Kai Michalke.
Michalke is out of contract in the summer but injury has meant Westley has yet to see the player in action.
The 30-year-old was expected at Pride Park for a short trial this week, where he would also have participated in a behind-closed-doors game, but he picked up an injury in Duisburg's Bundesliga match with Cologne at the weekend and did not travel to England.
"It was a pity in some respects as it was the last game we had arranged and we wanted it for him," Westley told the club's official website.
"But unfortunately he got injured while playing for his club on Friday evening so he was unable to come over.
"Now it's a case of either me flying over there after Sunday to have a look, us knocking it on the head, or we have another look at him in pre-season."
Meanwhile, on-loan striker Kevin Lisbie has been recalled by Charlton to cover a striker shortage at The Valley.
The 27-year-old scored one goal whilst at the Championship club and would have made his final appearance for The Rams on Sunday against Sheffield Wednesday.
"Kevin has done well for us and has led the line well so it is a blow to lose him," added Westley.