KIERAN Tierney faces the biggest decision of his career over the next few weeks as several English club are ready to meet Celtic’s valuation of £25million for their most prized asset.

Arsenal have tested the water with a £15m bid for the 22-year-old, which was immediately thrown out, while Everton, Leicester City and Napoli of Serie A are among his many admirers who believe this transfer window will see the left-back leave after years of him turning down lucrative opportunities.

Neil Lennon, the Celtic manager, yesterday admitted he would be “surprised” if his club doesn’t receive multiple bids for the best player to have come through the academy ranks since Paul McStay almost 30 years ago.

This is Lennon’s way of saying that it will happen - with Arsenal already making a move - which John Hartson, a former Celtic and Arsenal player, described as “embarrassing given the calibre of the player.”

And while French midfielder Olivier Ntcham is expected to leave this summer, and perhaps Callum McGregor, wanted by former manager Brendan Rodgers at Leicester, the loss of Tierney would be a sore one to take by supporters who rightly see him as the fan who plays on the pitch.

We understand that the interested parties are aware of Celtic’s asking price and those who have watched the three-time young player of the year are prepared to pay what would be the biggest fee ever for a Scottish player.

Lennon said: “Kieran has played a lot of football over the four years he’s been on the scene. I would be surprised if there is no interest from certain quarters. I would be very surprised if we don’t get offers for him – let’s put it that way.

“I’m not expecting a bid but I would be surprised if it didn’t happen given the calibre of the player. Then we may have a decision to make.

“I don’t know who would come in but even if they are mid-table clubs, they have plenty of money and are playing in the Premier League. I would be surprised if there wasn’t bids for a number of players here.”

Asked would an offer would be impossible to turn down if it met Celtic’s valuation, Lennon added: “It depends what the bid is. There is big money being quoted for players down there and Kieran is as good as then, if not better.”

Tierney’s love and commitment for Celtic is obvious but after three Trebles and many personal honours, there is not much left for him to achieve except being at the club if they win ten league titles in a row.

At 22, he has played 167 club games which has taken its toll on his body; he is currently in rehab following a double hernia operation and won’t play in the first round of Champions League qualifiers.

If he were to move to a Premier League team, there would be more rest between seasons, and he would not play as many games as he would at Celtic. He played 37 club games even during the last disrupted season.

Tierney, with appearance bonuses, earns £25,000 a week at Celtic Park, a wage that could be tripled by almost every club in English football’s top tier.

McGregor, too, has little else to accomplish with the club he joined at only eight-years-old.

He is one from within the Celtic dressing room who has kept contact with Rodgers.

The two have remained close and Leicester City could offer the midfielder, who turned 27 last week, a four-year deal which would set him up for life.

This is a crossroads for Celtic. On one hand, they would smash every record regarding money coming into the club during a transfer window.

But they would be losing some of their best players from recent seasons.

If Tierney, McGregor and Ntcham leave, Celtic would be looking at close to raking in £50m for two academy players and Ntcham who had a poor last season and cost £4.5m two years ago but is rated by Lyon and Marseille.

Celtic have never been so strong financially, however, chief executive Peter Lawwell knows that the board would never be forgiven if the blew nine and ten in a row when so close to breaking that world record.

David Turnbull will join his new team-mates next week, while Copenhagen right-back Peter Ankersen is believed to be close to having signing talks. Scott McKenna of Aberdeen remains a target.

Lennon said: “I think at least four before we play that first game (against Sarajevo). We have one in, David Turnbull, so another three. We are a bit light.

“We are thin in some positions, which we’ve known for a while. We are working on the hour, every hour, we speak top agents, Peter and we’ve Nick coming on July 1 and he has a great resume, experience and contacts. It’s all well. “

“A priority position we are looking to strengthen, no question, is centre-half, and we have a number of options that we’re running with at the minute.”

A complication regarding is the fitness of Jozo Siminovic whose past problems mean he can't play every game and not one on a plastic pitch.

Lennon admitted: "We have to manage Jozo. We know with his history he may not be able to do three games in a week, it’ll be Saturday to Saturday, and that’s fine.

“We’ve modified his training and not only did he play the majority of games at the end of last season for me, he played them very very well.

“So it's something we’ll address as we’re going along. If needs must in that scenario, we’ll play him, but if we can avoid it we will, for his sake.”