Mark Warburton's men have fallen to third in the Scottish Premiership following their defeat to Hearts on Wednesday night. However, they still sit one place and two points ahead of the Dons.
Rangers manager Mark Warburton
But Aberdeen are arguably in the driving seat in the race for second as they have currently played two games less than both of the two teams currently standing between them and Celtic.
And while Nicholas - who was speaking before the Light Blues' defeat to Hearts - suggested that he is somewhat expecting the Dons to move above the Gers when they meet on Saturday, he also warned Derek McInnes' men that a loss may prove crucial to Rangers' hopes of finishing second.
Aberdeen manager Derek McInnes
"The game against Rangers is now huge but it wouldn't be a surprise to me if they won that because they believe they're better than Rangers but that isn't the case with Celtic," he said, as reported by the Evening Times.
"There is a pressure on them now to beat Rangers because if Rangers can get some momentum then they could prove me wrong."
Though both sides go into the game having experienced a loss in their most recent game, it is perhaps Aberdeen that have a slightly bigger point to prove.
They were soundly beaten in the League Cup final last weekend, so may find it more difficult to bounce back than the Gers perhaps will.
Though they are so close in the table, it is fair to say that Rangers have been much more inconsistent in recent times, so they have more experience of responding well following a setback.