Former Celtic manager Martin O'Neill broke a 32-year spell without a Treble at Parkhead.
His 2001 triumph meant he joined only the legendary Jock Stein in winning all three domestic trophies – and so he's well aware of the immortality that awaits Ange Postecoglou if he can deliver the clean sweep this season.
With the Premier Sports Cup already secured in December, Postecoglou is just nine games from delivering what only Stein, O'Neill, Brendan Rodgers and Neil Lennon have accomplished in Glasgow's east end.