The Scotland left-back completed a £25million transfer deadline day move to the Gunners in midweek.
And he’s got right down to work continuing his recovery from a summer hernia operation while still a Celtic player.
There will be plenty of changes for Tierney while at Arsenal – and Bellerin had some advice for him on one of them.
As both players heading out for a session together at the club’s London Colney training ground, Bellerin told Tierney that he should get used to the cameras following him everywhere:
It’s not yet been confirmed when Tierney could make his debut for Arsenal, but fans will probably hope it comes as soon as possible.
He hadn’t made a first team appearance for Celtic this season while he recovers from that injury.
Arsenal kick off their Premier League campaign against Newcastle tomorrow.