Rangers manager Alex McLeish admits that his rebuilt side will only be judged a success once they beat Celtic.
Rangers and Celtic have both had their problems this season
His Celtic counterpart, Martin O'Neill, insists that, this time round, his champions are the underdogs.
But, after an unprecedented seven straight Old Firm defeats, McLeish said: "These are the games where ultimately the players get judged.
"If we are to achieve anything, we must finish above Celtic and we must beat them in cup competition."
Celtic, less than impressive in recent weeks, visit Ibrox in Wednesday's CIS Cup quarter-final to face local rivals who are unbeaten in their last 11 games.
"I don't think there is any doubt that winning breeds confidence," said McLeish.
"We have managed to string some good wins together and the team has steadily improved on the playing aspect as well.
"It was a new group of players that needed time to gel. You hear of players costing £30m in England and taking a whole year to integrate into the British game.
"I can't have any right to think that my players were going to gel after two or three weeks.
"There is no doubt we have more physical presence in the team, but this is a game that is difficult to call.
"I think Rangers and Celtic games, although Celtic have had the upper hand in recent games, are unpredictable.
"They can go against the form book. I think we have still got a lot to prove in terms of the last few games.
"But I have to say that six out of the seven derbies were lost by one goal. That is how close they can be."
Celtic have injury problems and O'Neill said: "Rangers are at home and, any advantage going, that's one.
"There is never too much between the two sides regardless of current form, which probably applies to most derbies and certainly the one up here.
"We have recently got a decent run against them, but that can change overnight, but we go there with plenty of confidence to try and win the game.
"Every single time we play Rangers it's a big test, regardless of form, and hopefully it's the same for them."