Rangers top the npower Championship but Billy Davies' men lie in third spot with games in hand on all of the top six.
Victory for Rangers would take them a step closer to automatic promotion but Derry told the club's official website: "I don't think that Sunday is crucial, not by any stretch of the imagination.
"But it's a big game. A lot of eyes will be on us, like when we played Cardiff a few months ago.
"We don't think it's going to be a deciding factor on what happens for the end of the season, but it's a big game."
Source: PA
Source: PA