Patrick McClean is ruled out while Ryan McBride, Aaron Barry, Dean Jarvis and Conor McDermott are all struggling to be fit and face late fitness decisions.
Derry lie third in the table, six places above their opponents.
The Candystripes have taken just one point from the previous two league matches between the sides this season.
"I respect Finn Harps immensely and I expect it to be a fantastic derby occasion," said Shiels.
"Their manager Ollie Horgan has done a fantastic job on a limited budget. They will go into the game with no fear but it's of paramount importance that we win.
"I'm always loathe to predict the outcome of derby matches as there are so many twists of fate involved and so many things can go against you, including the rub of the green with decisions."
The Brandywell men face an important encounter with second-placed Cork City on Monday night but the Derry boss is keen to adopt the old maxim of 'one game at a time'.
"I always say that the most important game is your next one so we will be concentrating solely on Finn Harps to begin with.
"We will just drive on and hope that our luck changes a bit in terms of performance and outcomes.
"We have played well in our last three games but only took a point apiece from the clashes with Sligo Rovers and St Patrick's Athletic, and lost to Limerick."
There will be live commentary of the game on BBC Radio Foyle 94.1FM and the BBC Sport website from 20:00 BST.
Derry City have injury concerns over a number of players ahead of their Premier Division derby against Finn Harps at Finn Park on Friday night.