HITC Sport understands League One trio battle for Northern Ireland striker.
Northern Ireland's Josh Magennis reacts after the game
The League One trio are keen to bolster their attacking options and have targeted the big target man before the close of the transfer window.
Oldham have seen their bid rejected with new Latics boss Stephen Robinson abig fan of Magennis having worked with the strikers as assistant manager of Northern Ireland.
Russell Slade keen on Josh Magennis
Charlton are also understood to have made a bid for Magennis as Russell Slade looks to bring the 25-year-old to the Valley, but Shrewsbury are now ready to enter the race for the forward.
Shrewsbury boss Micky Mellon is in the market for striking reinforcements after offloading Tyrone Barnett and James Collins this summer and he sees Magennis as the perfect foil to his other new signings in attack Louis Dodds, AJ Leitch-Smith and Antoni Sarcevic
- Northern Ireland's Josh Magennis (L) during second public training
The former Cardiff City striker has spent the last six years in Scotland with Aberdeen, St Mirren and Kilmarnock and he is thought to be keen on a move back to England.
Kilmarnock are reluctant to lose Magennis as the striker has established himself as a key player in Lee Clark's side, but they are facing a major battle to keep hold of him.
Kilmarnock manager Lee Clark