Celtic legend John Hartson believes toiling Rangers face a significant threat in their quest to retain the Scottish Premiership title.
Steven Gerrard and his players are reeling in the wake of their comprehensive 4-2 Champions League playoff defeat to Malmo that closed the door on a potential £40m golden ticket.
Rangers' three-game skid coincides with an upturn in Celtic's fortunes as Ange Postecoglou's side have netted 10 goals in wins over Jablonec and Dundee.
Hartson is quick to point out he retains Rangers as his title favourites but believes Celtic would be be in elite company if they were able to regain the Premiership instantly after losing out by 25 points last season.
Speaking to Go Radio, he said: "Celtic are on the up, if Ange was to go and win the league this season at Celtic, it would be the biggest league win of all time.
"When you think where Celtic have had to come from, changing the manager, he's come in with no director of football, no head of recruitment, he's almost picking the players himself, so we're led to believe. He's almost had to build a new team right from the goalkeeper all the way up to a centre forward.
"Listen, it can be done, I think there's a bit more investment to come in at Celtic - I think they will bring in another three, four, possibly five players before now and the end of August."
"They are going to even stronger again. I said at the start of the season it's Rangers' title to lose, I still believe that, on the strength of how well they did last season.
"But things can change very, very quickly in football as we know."
