Richard Foster has urged Neil Lennon to drop Shane Duffy from his starting lineup to get Celtic going again.
The former Rangers defender reckons his old side are now favourites for the title and has told Celtic to go back to basics if they want to improve their form.
Celtic stuttered against Aberdeen to go six points behind their rivals, although they do have a game in hand but Duffy's mistake for Ryan Hedges' goal has fans really worried.
And Foster reckons the stopper is struggling to deal with the chaotic pace of the Scottish Premiership as he told Sky Sports: "He (Lennon) probably has to make personnel changes. With Duffy coming in recently it looks like he’s struggled with the pace of the game in Scotland.
"Anything coming straight up and down he can go and head it but down the sides and players with pace like Scott Wright and Ryan Hedges yesterday, he doesn’t seem to enjoy it and I think he needs taken out and Celtic can freshen it up at the back and just be more solid.
"Yes, Celtic fans want to see them being expansive and scoring goals but at the moment their biggest weakness is in defence."
With Steven Gerrard's side now having a clear gap at the top of the table, they're playing with confidence that hasn't been seen by the Ibrox side in a long time.
But they did collapse after Christmas last year and Foster believes that is the only doubt on whether they can go on and clinch title 55.
When asked if Rangers were favourites, he said: "I think so. I know they haven’t gone the course yet and the last nine years it has been Celtic and Celtic know how to get over the line, but there’s been a big difference in what we’re seeing on the pitch for both teams.
"If you look at the bench, Kemar Roofe scores an amazing goal but can only get a place on the bench, Cedric Itten comes on, Jordan Jones is looking back to his best, they do have the depth in the squad.
"Scott Arfield has been one of their best players this season and couldn’t get in the team. They’ve got everything they need, they’re playing well, they’re confident, they’re scoring goals, solid at the back and right now they are the form team in Scotland."
