Both Celtic and Arsenal picked up wins during their respective Europa League clashes - Neil Lennon's side saw off CFR Cluj, and as mentioned above, the Gunners eased past their Belgian opponents.
Tierney moved to the Emirates Stadium over the summer, but he has had to wait a little while to make his first appearance for the club because of an injury.
He made his debut during Arsenal's League Cup win against Nottingham Forest, and now in his second start for the club, he has already provided an assist.
This was the simple message Brown sent to Tierney, as he was seemingly watching back the highlights of Arsenal's game after Celtic had recorded their own win at Parkhead.
Celtic supporters will be well aware of what Tierney is capable of and it won't probably be until another couple of months until Arsenal fans see the real Tierney.
It needs to be remembered that he has suffered a number of injuries recently and with hardly any pre-season action under his belt, he's going to need time to get some serious sharpness into his legs.
Both Celtic and Arsenal will have high ambitions of winning the Europa League, and if they can go deep into the competiton then there might be the possibility that they could meet. And if they do then it'll be some contest and story for Tierney.
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