FCK will host the first-leg of the Champions League round 16 tie on Tuesday.
Jelert famously crunched Grealish in the opening minutes of their previous meeting two years ago.
"Yes, I remember that well," he told Bold.
"It can be one of the things you can put into use, and if that's what it takes, then that's what you have to do.
FC Copenhagen is in a much better place now than what was the case two years ago, Jelert believes.
"We are better now. Without saying anything bad about our squad then, it is better now. We have also come further than we did last time, so I think we are doing that."