Graeme Souness believes Rangers will be under pressure if they lose at Celtic Park on Saturday.
The in-form champions have won all five Premiership games this season and are two points clear of rivals Ibrox at the top of the table, following their 9-0 humiliation of Dundee United at Tannadice on Sunday.
Giovanni Van Bronckhorst’s side are also tops after qualifying for the Champions League for the first time in 12 years, but their 2-2 draw with Hibernian at Easter Road recently left them chasing Celtic .
Rangers face Queen of the South in their Premier Sports Cup round of 16 at Ibrox on Tuesday night, while Ange Postecoglou’s men travel to Ross County the following night in the same competition, but after that, the focus will be on Parkhead and the first Old Firm game of the season.
Souness, who was a player/manager at Rangers between 1986 and 1991, knows the importance of the game and told TalkSPORT: “Both teams go into it with their heads held high.
“No one, myself included, expected Rangers to qualify for the Champions League. Their tails are up.
“My experience working in Scotland is that you could play the best football, the best team, but you’ve drawn a draw and you’re second to, in my case, Celtic.
“All the pressure is on you to move forward.
“Celtic, at that time, might not be playing such good football, but they are top of the league, they’ve gone and run without any pressure on them.
“So this game is vital, vital because if Rangers were to lose it would be them five points behind and then all the pressure would be on Rangers shoulders.
“Then Celtic might continue to not play very well from week to week, but as long as they are number one the pressure is on their shoulders and play with a bit more freedom.
“It’s a big game so early in the season.”
The former Liverpool and Scotland captain, who captained Anfield, Galatasaray, Blackburn and Newcastle – among others – still believes the Glasgow derby is a knockout opportunity.
He said: “It’s the biggest derby. Galatasaray/Fenerbahce, Everton/Liverpool, Liverpool/Man United are huge matches, but this is beyond them.
“Whether it’s because Scotland has five million people, the spotlight, there’s nothing else in the papers, all the preparation, the pressure is very high on the players to come out and play.
“The whole country is looking at the situation and there is usually a drama, usually some sort of thing that is wrong for an individual or a team.
“I’ll come back to it. The last thing you say is “start off on the right foot”. Be up front because if you fall behind in this game it’s hard to get it back.