Kris Commons has claimed that Rangers require "tens of millions" of pounds of investment before they can consider themselves equal to Celtic.
The Hoops have a chance to move a step closer to successive domestic trebles under Brendan Rodgers when taking on their Old Firm rivals in the semi-final of the Scottish Cup this weekend.
Despite being 13 points behind Celtic in the Scottish Premiership, Gers chairman Dave King has told whoever takes over at Ibrox permanently that winning the league is the target next season.
Former Celtic midfielder Commons has questioned Rangers' ambitions, though, insisting that there is still a huge gulf between the two clubs.
"It's quite ironic [King's] not singling out Graeme Murty for that role," he told Sky Sports News. "The next manager, whether it's going to be Graeme Murty or someone else, needs to have ambitions to win the league. I think it's very ambitious.
"I heard [Rangers defender] James Tavernier say he wants to win a treble as well. There's a lot of noise coming from Rangers of what they want to do. Put quite simply, they need to invest in the squad to give them the best opportunity for that.
"That's going to take tens of millions in my opinion. They've got a lot of loanee players returning to their old clubs. And then they're back to where they were about 12 months ago.
"At this minute in time, they're a little closer to Celtic but in the grand scheme of things they're still way, way behind winning a title."
Celtic finished 39 points above their Glasgow rivals in 2016-17.
