Grezda could be available to start for Rangers on Saturday.
Steven Gerrard left Liverpool in the summer to join Rangers.
Now could be the time for Steven Gerrard to hand Gareth McAuley his Rangers debut, with Nikola Katic injured and a hectic schedule coming up.
Some Rangers fans think the Ibrox pair could be next to break into Steven Gerrard's plans.
John left Rangers after Steven Gerrard signed two new left-backs.
Steven Gerrard's Rangers have announced a three-year partnership with their Canadian namesakes, whose youngsters could train at Ibrox.
Docherty left Rangers in the summer to join Shrewsbury Town on a season-long loan.
Rangers were linked with a move for Bournemouth defender Simpson in the summer.
The Rangers midfielder was allowed to leave Ibrox on loan by Steven Gerrard.
Plenty of players have improved at Rangers since Gerrard was appointed.