Steven Gerrard has accused Aberdeen of trying harder against his Rangers side than they do when they face other teams.
Rangers have struggled to get the better of the Dons this season, especially in Glasgow.
Derek McInnes' side have knocked the Light Blues out of both cup competitions with victories at Ibrox and also tasted victory on their last Ladbrokes Premiership visit.
They will be looking to make it a clean sweep when they head south for the final meeting of the teams this season on Sunday.
But Gerrard says the Dons have not always shown the same effort levels as they do when facing his team.
"Aberdeen play differently against Rangers," said the former Liverpool captain.
"That's what I've noticed. They certainly raise their game. It seems as if Rangers is their biggest game of the season.
"Do they try harder against Rangers? That's the way it looks on the eye. We watched them last week against Celtic and they never laid a finger on Celtic in the semi-final.
"They obviously come to play against Rangers and bring their A game. They're very physical and they definitely lift their game against Rangers, that's for sure.
"I suppose they know they have to be at their maximum to stop us. There have been some good battles. They have had the upper hand in the cups, knocking us out. But as the league stands we've done slightly better.
"I'm not saying they don't raise their game against Celtic but they have found their form definitely against Rangers. And having watched them against Celtic a few weeks ago it wasn't the performance you expect from Aberdeen if you look at their performances against Rangers."
