RETURNING Greater Western Sydney ruckman Shane Mumford has seen his pre-season preparations hampered by a hamstring injury sustained prior to Christmas.

Mumford suffered the low-grade hamstring strain on the Friday before the club left for its Christmas break, with the 32-year-old subsequently placed on a modified program.

The Giants expect he will rejoin the main group midway through January and do not anticipate the setback will harm his chances of featuring in the early stages of this season.

Mumford returned to GWS in December, signing for the club as a rookie just a year after he retired from the game due to a series of debilitating injury problems at the end of 2017.

He has been suspended for the first two matches of the 2019 campaign after a video surfaced of him snorting a white powder prior to his AFL comeback, while he was also fined $25,000.

Mumford, who has played 172 career games and was the Giants' 2014 best and fairest winner, acted as the club's ruck coach throughout the 2018 season.

His return will aid the Giants' thin ruck stocks, which were depleted when Rory Lobb returned to his native Western Australia to join Fremantle during the NAB AFL Trade Period.

Dawson Simpson, Kieren Briggs and Matthew Flynn are the club's other available rucks.