Barry Ferguson believes a defeat for Rangers at Ross County on Sunday would be “unthinkable”.
Pedro Caixinha’s side have made a disappointing start to the Scottish Premiership campaign and already trail rivals Celtic by five points after just three games.
Ferguson told the Daily Record: “Falling eight points behind Celtic and Aberdeen with only four league games played and an international break looming? Unthinkable.
“Rangers must not head into the first Old Firm game at Ibrox on September 23 any further behind than the five-point gap and must also pray Celtic drop at least a couple of points between now and then.