It is not the arena in which Celtic wanted to be this season, but the Europa League is where Ronny Deila will be judged.

That is the view of Jim Craig, the Lisbon Lion, who has also acknowledged concerns about some of the decisions that Deila has made since taking over at the Scottish champions. Celtic will tonight play in their second Europa League group match, against Dinamo Zagreb, and Craig believes that the Norwegian coach must provide a positive result to help win over supporters.

"Let's be honest, the league will be a formality but it is in Europe where Deila will be judged," said the former Celtic full-back. "The fans are not convinced about him yet as a manager coming in from the Norwegian league. They need to be won over but as yet that's not happening, as was shown with just 15,000 turning up for the Hearts game last week.

"A good European campaign would be a big boost. They made a good start with the draw in Salzburg but they could do with putting some positive results on the board, especially at home. That is the bigger picture. Celtic want to mix with the big boys in the Champions League but they screwed that up for one reason or another.

"It's not been easy for Deila. He has came into a scene he knew nothing about and take over from a manager who did very well. It's been a tough start for him. It takes time for a new team to gel.

"They are not playing that well but it wont happen instantly. I don't think, for example, that you can throw a central defensive partnership together overnight. It takes time for a defence to get to know each other but there has barely been the same side one week to the next."

Craig continues to extol the success the Parkhead club enjoyed under Neil Lennon, but acknowledge that the Northern Irishman must now work just as hard to secure a coaching job in England. "I said to him when we were in Lisbon recently to be on the television and radio as much as possible as you need to keep yourself out there for positions that come up."