The present disclosure relates generally to gaming systems and, in particular, to back-betting within a gaming system. As an example, a back-betting system is disclosed to include a first communication interface that facilitates machine-to-machine communications with an Electronic Gaming Machine (EGM) of a gaming system, where the first communication interface is used to exchange state-of-play information with the EGM. The system is also disclosed to include a second communication interface that facilitates machine-to-machine communications with a mobile device, where the second communication interface is used to exchange back-bet wager information and deliver an indication of an outcome of a back-bet placed during a back-betting session established with the mobile device. The system may still further include a processor and a computer-readable storage medium with processor-executable instructions that limit a duration of the back-betting session based on an association existing between the EGM and the mobile device.