Former Celtic and Borussia Dortmund great Paul Lambert has shared his thoughts on what went wrong for the Parkhead side in Germany, as Brendan Rodgers' men lost 7-1 on the road.

The former midfielder is well-acquainted with the fierce atmosphere the home crowd is capable of generating inside Signal Iduna Park, which is one facet Lambert reckons Celtic struggled with on Tuesday night (October 1).

Reflecting on the match on talkSPORT on Wednesday morning, Lambert said: “I never said it yesterday, but that’s exactly what can happen in that stadium. You’ve got to be a big, big player there to handle that atmosphere. If you don’t handle that, that’s exactly what can happen.

“And I think there’s going to be criticism coming Celtic’s way, but I think you’ve got to put it into perspective."

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Lambert suggested that the financial disparity between the two sides was another key component of what went wrong for Celtic in Germany, while also criticising the gulf in class within Scottish football itself.

He added: Celtic aren’t playing a St Johnstone, playing a Hibs, playing a Hearts. You’re playing a team, albeit five of those eleven played in the Champions League final last year.

“So you’ve got to look at it in comparison with, rather than analyse it as a fan. I think you’ve got to look at it and say, ‘Well, how did that happen?’ “The standard of football in Scotland is nowhere near the same and that is a major problem.

"I think there’s an insular perception of Scottish football that we’ve got some really good teams, we haven’t. The level is not there anymore.

“When I played in the Seville game the year Martin O’Neill had was a phenomenal era. Celtic can’t compete with Borussia Dortmund financially. Rangers are an absolute mess at the minute so they can’t compete.

"But you’re talking clubs that are global, worldwide football clubs that can fill any stadium in the world if you give them the ticket base but there’s no way that Scottish football can compete with teams like that, Borussia Dortmund, it’s impossible for them to do it because of the revenue."