Martin O'Neill surely would have gotten assurances over Celtic's transfer plans before committing to signing on as the club's permanent manager this summer after winning the league and cup double as interim boss in the previous campaign.

While Celtic might have been successful in making a late charge and winning the double, they were not able to meet the expectations that is set for the team by the supporters. The performances were not good enough. They scored less and conceded more, significantly so in both departments.

The summer transfer window is a chance for them to improve their squad. Reinforcements are needed all across the pitch.

One of the areas where Celtic seem to be keen on strengthening is their defence. And it looks like they have mde their move for a highly-rated defender.

According to Rudy Galetti, Celtic have submitted an improved offer for Zinedin Smajlovic worth €4.5m fixed plus another €2m in bonuses.

Sandefjord are under no pressure to part ways with Smajlovic. Olympiacos, Hull City, Rangers, Fenerbahce, Toulouse, Feyenoord and Lyon are all closely tracking the defender and have made enquiries.

So, it is safe to say that there is a decent level of interest in Smajlovic. And that has been a topic of controversy in the Scottish media as well.

Earlier, news had broken out that Celtic had made an offer in the region of €4.5 million to sign Smajlovic.

But that was questioned in the Scottish media and it was claimed that no such bid had been made by Celtic.

Now, there is fresh speculation about Celtic making an improved bid to try and sign Smajlovic. What is accurate? What is not? It is very hard to say as things stand.

READ MORE: Celtic Transfer Target's Next Club Confirmed

Celtic could certainly do with another option in the heart of defence right now. They had Auston Trusty and Liam Scales starting there last season.

That is not the most natural fit though. Both of them are left-footed. It makes the angles awkward, both while building out from the back and defending opposition attacks, especially when it comes to the one playing in the right centre-back role.

On the other hand, Cameron Carter-Vickers has been dealing with another long-term injury. And there are many who feel that we will never see him performing at his best again, given the sheer number of fitness issues that he has had to deal with over the years, going back to his second season in Celtic colours.

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