This summer transfer window is going to be a vital one for Celtic. To be fair, the Hoops could still finish the campaign with a Premiership and Scottish Cup double. But even then, one has to admit that they have not been anywhere near the mark.

Celtic's form has dipped considerably over the last 18 months or so. The last time we saw them consistently perform at a high level was back in the first half of the 24/25 campaign.

So, the Celtic squad needs to undergo a bit of a revamp this summer. Fresh faces need to be brought in. Just not to make up the numbers but to add some genuine quality as well.

On the other hand, the club will need to make sure that they keep their best players around and do not lose any more quality than they already have over the last few years.

Arne Engels is someone who continues to be linked with a move away though. Celtic turned down about £25 million to part ways with him in the winter.

But if big clubs come calling, it might not be long before the player's head is turned. And it looks like one of the biggest in Europe have him on their radar now.

According to Football Insider, Borussia Dortmund are the latest side to join the race to sign Engels. The Bundesliga giants are now readying a move for him and could step up their interest.

If a club like Borussia Dortmund do end up making a concrete offer for Engels in the summer, it might be a tough time convincing him to stay.

In the long run, it might represent some good business for Celtic, who spent about £11.5 million to sign Engels and could be set to pocket a tidy transfer profit when he does leave, whether it be this summer or further down the line.

If Celtic do end up sanctioning Engels' exit, they will need to find a quality midfielder to replace him. And that might mean breaking their transfer record once again.

It is worth mentioning that Engels is not the only midfielder to be linked with a Celtic exit at the moment. In fact, pretty much the entire midfield could be on their way out if reports are to be believed.

Callum McGregor, Reo Hatate, Benjamin Nygren and Paulo Bernardo are all believed to be potential departees this summer.

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