Alexander Isak is arguably the most-talked about striker in world football right now. More than Erling Haaland, Kylian Mbappe, Harry Kane.

The Swedish superstar is in such a rich vein of form that he is making headlines every game. 14 goals in his last 15 outings, a calmness in front of goal and with an all-round ability that could see him operate in a number of positions, there's no wonder envious glances are being cast Newcastle United's way.

It has been said on more than one occasion that Isak is not for sale this transfer window. Newcastle wouldn't entertain any bids for a player they rate at £150million, and nor does the player want to leave Tyneside. The best striker currently in Europe is happy in black and white.

READ MORE: Miguel Almiron airport picture explained as agent breaks silence on Newcastle United 'offers'

READ MORE: PIF move to 'strengthen' Newcastle United after new director made himself clear on two offers

That hasn't stopped every pundit, ex-player and presenter being asked about whether he would be a good signing for Arsenal, Manchester United, Real Madrid or elsewhere. In some ways it is testament to how well Newcastle boss Eddie Howe has got him playing - how often is a United player coveted by the biggest clubs in Europe?

Former England, Liverpool and Aston Villa forward Emile Heskey is the latest to be asked about Isak and a potential move to Arsenal in his role as an ambassador with Instant Casino. To be fair to Heskey, he swatted away the question, asking why Newcastle would sell the 25-year-old to the Gunners this month - not least because there is 'no love lost' between the two clubs.

Of course, the summer is a different conversation. Newcastle fans are acutely aware that their ability to hold on to their best players like Isak, Anthony Gordon, Sven Botman and Bruno Guimareas may well depend on whether they can offer what most footballers want in their career - Champions League football.

They've tasted it previously; Howe inspired the Magpies to a top four finish two seasons ago and with United on a hot streak, they are targeting a return to Europe's premier competition. Heskey admits that it may be the crucial factor at the end of the season - and queried whether Newcastle and the player may have a 'gentleman's agreement' to allow him to leave if they don't qualify..

He said: "I think Arsenal fans are living in dreamland if they think that they can sign Alexander Isak in January. The thing is, Newcastle are legitimately chasing top four.

"If I'm Eddie Howe, do you seriously think that I’'m going to sell my best player to a rival? There’s no love lost between Newcastle and Arsenal, so why would they want to do them a favour.

"I think it would take stupid money, crazy money to get Isak out of Newcastle in January. Even if they want him in the summer, you're talking over £100million. Will they try for him in the summer? Maybe, but who's to say he wouldn’t want to stay at Newcastle, especially if they can secure Champions League football.

"If Newcastle do qualify for the Champions League, I can't see them selling any of their best players. For every player, the Champions League is where it's at. It's the pinnacle in club football.

"So, I think to keep a player like that, there might be a gentleman's agreement between him and the club where they will allow him to leave if Champions League football isn’t on the St James' Park menu."

With Isak in the form he's in, and the players around him also performing superbly, there is every chance a European place will be garnered when May comes around. If not, it will still take 'stupid, crazy money' to force Newcastle to sell a player who still has three years left on his contract. Arsenal, Man United and anyone who comes calling should be warned that the bidding starts at £150m.