Celtic have received their first "concrete bid" for defender Josip Juranovic, according to reports.

The Croatian has been the subject of increased transfer interest ahead of the January window following an impressive showing for his country at the World Cup.

Juranovic helped Croatia to a third-place medal at the tournament and he enjoyed some standout displays from his right-back berth.

Manchester United, Chelsea, Atletico Madrid, Barcelona and Monza have all been linked with the 27-year-old in recent weeks.

But Italian outlet Tuttomercato now say that Espanyol are leading the chase for Juranovic's signature as they claim the La Liga outfit have submitted a bid for his services.

The report goes on to state that Monza will not back down and they could also table a bid in the near future.

On the transfer interest in his defender, Celtic boss Ange Postecoglou said recently: "I can say that I've heard nothing. Nothing's happened. As I said a week or so ago, the speculation is what it is.

"What I know is that we are in a really good space as a club. Going into January, we have already strengthened and hopefully we'll strengthen even further.

"I’m in no doubt that by the end of January we’ll have a stronger squad than we did going into it."

Meanwhile, Celtic defender Alistair Johnston has called for consistency from match officials after being surprised his side did not get a penalty at Ibrox.

Rangers centre-back Connor Goldson appeared to block Carl Starfelt’s effort with two hands raised to his face during Monday’s 2-2 draw.

But referee John Beaton played on and video assistant referee Willie Collum did not call him to the monitor.

Johnston felt Goldson’s actions did not look right at the time and his feelings were reinforced by watching footage.

“I was actually in the box, and I kind of put my hand up because it just felt something unnatural had happened,” said the Canada international, who was making his Celtic debut.

“It happened so fast, you couldn’t really tell. After the match, you see the replay, and I think it’s hard to argue that is a natural hand position.

“As a defender especially, you put your hands up there, you generally run the risk.

“So for me obviously I thought it was a pen. I sound a little biased here but it is what it is. It’s a 90-minute match and there were so many other moments where we could have done better, where you are not putting the match in someone else’s control.

“We don’t look at it like VAR screwed us – it was a decision that went against us, but there will be plenty that hopefully go for us and others that go against us.

“All we ask for is just consistency, that’s the biggest thing you want as a footballer.

“As a defender especially now, you are pretty much told you can only defend with your hands at your side, and you see a lad putting his hands to his face and not getting called for a pen.

“If you see one of us give up one in a couple of weeks where it’s similar and they call it, there are going to be some questions asked. As long as it’s consistent, we are happy with it.”