Dundee assistant manager Simon Rusk felt let down by the officials after they awarded James Tavernier a penalty in his side's 3-0 home Scottish Cup defeat to Rangers.
The visitors were a goal up when Tavernier was bundled over by Ryan Sweeney inside the box midway through the first half.
And match official Steven McLean showed no hesitation in pointing to the spot.
Rusk told Premier Sports: "Obviously we're disappointed with the decision for the penalty.
"I've not actually seen it back yet. I've been told it's soft.
"Rangers were always going to cause us problems. We perhaps didn't deal with those problems they were offering well enough early in the game."
Rusk, who was deputising in the absence of manager Mark McGhee, knows the cup exit isn't season defining as the Dark Blues fight at the foot of the table domestically.
But he believes improvements are needed for the same fixture against the title hopefuls in the league next Sunday.
"The result is the result. Obviously disappointing because it's the cup," added Rusk.
"The early goal causes us lots of problems and then from there it's keeping your shape and trying to find that balance of just staying in the game but not taking to much of the game that you are out of it.
"We have to be mentally tough. We have to look at the game. What can be better and take it into next week's fixture against the same opponents."
