GLASGOW, SCOTLAND - OCTOBER 23: Rangers manager Mark Warburton looks on during the Betfred Cup Semi Final match between Rangers and Celtic at Hampden Park on October 23, 2016 in Glasgow, Scotland. (Photo by Ian MacNicol/Getty Images)

GLASGOW, SCOTLAND - OCTOBER 23: Rangers manager Mark Warburton looks on during the Betfred Cup Semi Final match between Rangers and Celtic at Hampden Park on October 23, 2016 in Glasgow, Scotland. (Photo by Ian MacNicol/Getty Images)