Arsenal Reportedly Optimistic Despite Kieran Tierney Bid Rejection by Celtic

Celtic have reportedly rejected an opening bid of £15 million from Arsenal for full-back Kieran Tierney, but the Gunners are optimistic a deal will be made.

Per BBC Sport's David Ornstein, negotiations with Celtic are ongoing, while it is believed the Gunners and Tierney should easily agree to personal terms:

Betting company Ladbrokes believes £15 million isn't nearly enough for the Scottish international:

Former Gunner and Celtic man John Hartson agreed:

The Celtic academy product made his debut in 2015 and has been a regular for the Scottish giants for four years.

He's won the Scottish Premiership with the club in five straight years—although he made just two appearances in the 2014-15 campaign—and he has claimed the PFA Scotland Young Player of the Year three times. 

The left-back has long been regarded as one of the best talents in Scotland, and a transfer south of the border seems just a matter of time. 

He has previously been linked with Manchester United, per Daily Mail's Jack Gaughan, while Tottenham Hotspur have also been credited with an interest in the past, per the Mirror.

An attacking specialist, Tierney has bags of athleticism and excellent positional awareness, while he can also contribute with goals and assists. Defensively, he's a work in progress, but at the age of 22, he has plenty of room for growth.

A full-back duo of Tierney and Hector Bellerin could do plenty of damage next season, but Arsenal will have to put a far better offer on the table to make that a reality.