Arsenal are said to be confident of completing a deal for Celtic left-back Kieran Tierney.
Unai Emery is interested in the Scotland international as he looks to freshen up his defence this summer.
Nacho Monreal extended his contract by another 12 months but could be sold with a return to Spain on the cards while Emery has doubts over Sead Kolasinac's defensive credentials.
Arsenal made a £15m approach for Tierney plus a player, although that was rejected by Celtic as they hold out for closer to £25m.
But the Gunners are expected to return with an improved £19m offer for the 22-year-old.
Arsenal are confident of reaching an agreement over the transfer though with personal terms unlikely to be an issue, reports BBC Sport.
Tierney is currently recovering from surgery to solve a niggling hip problem but should be back in time for the new season.
Meanwhile, former Arsenal and Celtic striker John Hartson has slammed the offer for the defender.
"My old club Arsenal testing the waters with reported £15m bid for Kieran Tierney," he posted on social media.
"Celtic don’t want to sell besides that in this current market £15m is an embarrassment to the player and his ability."
Arsenal boss Unai Emery has been given a strict transfer budget of just £40m this summer following the failure to qualify for the Champions League.
Ryan Fraser and Yannick Carrasco are targets but initial approaches have not proved successful so far.
Emery is likely to raise funds through player sales with Mesut Ozil and Henrikh Mkhitaryan up for grabs, although they have not generated any interest as yet.
