Rangers summer signing Ryan Jack and former Celtic midfielder Paul Hartley played together at Aberdeen.
Dundee manager Paul Hartley speaks highly of Celtic midfielder Scott Brown.
Mark Warburton's Rangers side play host to Dundee at Ibrox tomorrow.
The Celtic captain has been in fine form at the beginning of this season.
Paul Hartley says he will not sell anyone this summer.
The Dundee striker has been linked with Leeds United, Aston Villa, Queens Park Rangers, Derby County and Bolton Wanderers.
Dundee FC manager Paul Hartley reveals he wants to keep hold of Leeds United target Greg Stewart.
The likes of Rangers and Leeds United have been linked with the forward.
Ronny Deila is leaving Celtic this summer - who could replace him?
Remi Garde has lost his job as Aston Villa manager - who could replace him?