STEFAN JOHANSEN has insisted that his manager and fellow Norwegian, Ronny Deila, has the mental strength to handle anything which comes his way at Parkhead.

Deila has come in for frequent criticism in his opening months in Scottish football and Celtic have yet to deliver the results which would convince all their supporters.

Previous managers have folded under the pressure of dealing with what comes with being in charge in Glasgow. But Deila has stuck to his principles and even been outspoken enough to distance himself from the way things were done under his predecessor, Neil Lennon.

Johansen knows Deila better than anyone at Parkhead having played under him at their former club, Stromsgodset, and yesterday he gave him a glowing endorsement.

"Could criticism break Ronny? No, I don't think so. He is strong mentally. He believes in what he does and if he doesn't succeed with that he can be proud of trying. But I'm sure he's going to succeed."

Lennon won three league titles, two Scottish Cups and reached the last 16 of the Champions League with Celtic and Johansen said Deila was capable of delivering a similar level of success.

"He didn't have the same pressure on him at Stromsgodset but the way he has handled the pressure [at Celtic] he hasn't shown any weak points," said Johansen. "He's strong mentally and he believes in what he does.

"I didn't see that side of him at Stromsgodset because there wasn't that pressure but now when he has that he has handled it well. He hasn't changed, he believes in the football he wants to play and I'm starting to see that get better."

Johansen joked that he was sometimes teased by team-mates for being the teacher's pet, but without foundation. "We know each other from before because he was my gaffer in Stromsgodset as well, it's not like we're close or something like that. He's takes care of all the players the same."

Having lost their last home fixture to Hamilton, Celtic lifted the mood with a comprehensive rout of Ross County in Dingwall at the weekend, with Johansen especially impressive in a playmaking role.

Another win at home to the Romanians, FC Astra Giurgiu, tomorrow night would put the Scottish champions on seven points after three games in Group D of the Europa League.

Despite the inevitable comedown of playing in the lesser competition rather than the Champions League, Celtic have made a reasonable job of keeping their fans engaged. There was a lively atmosphere during the home win over Dinamo Zagreb despite the stadium's top tier being closed on the night. "We cannot do anything more than win games and play good football," said Johansen.

"I don't like it when half of the stadium is closed, I want it to be full but it's difficult because it's not the Champions League. If we get through and we start to win matches then I think the fans will start to come back because it's such a great support. That is the type of pressure you have at Celtic and you've got to deal with it. I don't think the players or the gaffer see that as a problem."

Johansen was pleased that Lennon, the manager who brought him to Celtic, got off to a winning start with his new club Bolton at the weekend but admitted that if he had the choice reportedly available to Kris Commons - who is wanted by Lennon - he would stay at Parkhead.

"I would be at Celtic. England is England of course but to be at Celtic is to be at a fantastic club.

"I said when I came here that Celtic are one of Europe's biggest clubs and I'm still saying that. So I would prefer Celtic. When you talk about clubs such as Manchester United you are talking about big clubs but Celtic are a huge club. It's just rumours as Kris is enjoying life in Glasgow and he's done well for the club and hopefully he will stay."

Meanwhile Johansen said he was still baffled by the booking he received while playing for Norway against Bulgaria last midweek.

He made a sliding tackle near the touchline which went on to bring down Bulgaria coach Luboslav Penev on the trackside.

"I've never experienced something like that in my life. I tried to slide for it and the guy was there. He reacted angrily and I didn't like that. There was no problem, I shook his hand. But suddenly the ref gave me a yellow card and I don't know why."