Neil McCann fears Rangers ' Champions League dream could quickly turn into a nightmare unless they get their act together.
The pundit and former Ibrox star was left stunned by Giovanni van Bronckorst 's side being dismantled at Celtic Park on Saturday. Rangers were battered 4-0 by their city rivals just days before they embark on a first campaign at UEFA's top table in over a decade.
They face in-form Ajax on Wednesday knowing vast improvement is required following a disastrous afternoon at the home of their city rivals. Liverpool and Napoli also lie in wait for Van Bronckhorst's team, who have proven themselves capable on the European stage. But McCann insists they can forget making an impact against the continent's elite unless they cut out the errors that cost them so dearly against Celtic. He said on BBC Sportscene: "Rangers, I do believe they've got the ability to come out of it but they need to stop putting on abject performances. They need to switch on. If they switch off like they did against Celtic today, they won't get very many points."
Celtic also kick off their Euro campaign this week, hosting current holders Real Madrid at Parkhead on Tuesday. Postecoglou's team have been in scintillating attacking form and McCann reckons they have enough to trouble the La Liga champions.
He said: "I'm really looking forward to seeing both games, I actually think this Celtic team could give Real Madrid some real problems.
"It's in the forward areas that they have to defend against Real Madrid, where they've got so much quality, whether they can keep them at bay.
"But I think it'll be a wonderful night for Celtic taking them on because it'll give Ange a mark of where they're at."