The World Cup is just a couple of days away from starting. Despite that, it looks like clubs' transfer plans are already in overdrive. And Celtic might find themselves at the centre of it.

This is expected to be a busy summer for Celtic. The double might have been great for the Hoops, but they cannot overlook how poor they were for the majority of the campaign.

Overall, they managed just 82 points in the league. That is five more than what they could gather in the 20/21 campaign. It might have been enough this time around, but it won't be in the future. They need to get much better.

The easiest way to do that would be to sign quality players who are ready to be starters immediately.

But instead, it looks like key players from Celtic are being linked with moves away from the club at the moment and are drawing serious interest from clubs in the Premier League.

According to Anthony Joseph, Nottingham Forest, Sunderland and Fulham are all interested in Arne Engels this summer.

Nottingham Forest had a number of bids rejected for the Belgian midfielder in the January transfer window. The final one was £25 million on Deadline Day.

Of course, when there is that level of interest in a player from the Premier League, it is hard for Celtic to hold on to them.

That £25 million figure is a record fee in Scottish football. And if any of those clubs come calling in the summer, one would imagine Celtic would want at least something in that region, if not more.

The club might find it difficult to turn down a fee in that region again, even if they did so in the middle of the season, which was without a doubt the right decision.

READ MORE: Celtic Tipped to Sign 17-Goal Forward from Scottish Rivals

Engels might not always get the credit that he deserves but he most certainly is someone who has a positive impact on the team.

Celtic were probably at their best in the final stretch of the season. And they won all eight games following Engels' return from injury. That is impressive when you consider how shaky their form had been all season.

Now, let us turn our attention back to the matter at hand, which is Engels' future. It is more than likely that Daizen Maeda and Reo Hatate will both leave this summer.

If someone of Engels' quality does as well, Celtic will leave themselves with a mountain of a rebuild. Are they capable of pulling it off? Or would they be painting themselves into a corner they cannot get out of?

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