The ex-Hoops striker feels that the depth of Ally McCoist's 'Gers squad is not very strong and has indicated that any slip-ups in terms of injuries to key players could let Celtic right back in for the title race.
"Rangers are still fragile in my opinion. They'd be tested if they lost a couple of players to injury," he told the Daily Record.
"This isn't the strongest Ibrox team of all time by any means and I still think Celtic have a stronger squad.
"I give them full credit for winning three titles in a row but the defeat by Maribor in the Europa League told me all about Rangers' frailties.
"The Slovenians were a poor side on the evidence of what we saw in the first leg but they were still able to go to Ibrox and win their way through to the group stage on aggregate.
And Sutton added that Celtic boss Neil Lennon is doing a good job but the players need to come to the party by recording the desired results.
"The loss to Hearts would have been more disappointing for Neil in terms of the way his team performed," he added.
"I came from a team full of guys who weren't afraid to say things in the dressing room. Sunday's team were not adaptable enough in their own minds when things were going wrong."