​Arsenal could end up missing out on Celtic left-back Kieran Tierney, as they are unwilling to match the Scottish champions' £25m valuation for the defender, with Serie A side Napoli set to hijack the move.

The Gunners are reportedly going all out for Crystal Palace winger Wilfried Zaha, and as a result may not be able to pay the fee demanded by Celtic.

Wilfried Zaha

​The Sun report that Napoli are now at the front of the queue to land a move for Tierney, with the club willing to meet Celtic's valuation as Carlo Ancelotti looks to bolster his squad in an attempt to dethrone Juventus next season. 

Arsenal's negotiations for Zaha are likely to drag out through the window, leaving Tierney on the backburner, and the player may already be in Naples by the time Arsenal are able to submit a bigger offer.

​The Gunners submitted an initial bid for the Scottish international, but manager ​Neil Lennon said that the offer would have to be a lot higher if they are to be tempted to sell one of the biggest names in their roster.

Kieran Tierney

Tierney was one of Celtic's best players last season, getting five assists in 20 appearances in the league, and the Scottish club are unwilling to part company with him easily.

Arsenal's frustrations in the transfer market can be traced back to their failure to qualify for Champions League football next season, resulting in a meager estimated transfer budget of £45m. 

This has made negotiations for a number of players much more difficult, with negotiations for summer targets Yannick Carrasco and Ryan Fraser also coming to a standstill due to a lack of funds.