Promising Rabbitohs five-eighth Luke Keary will miss the next four to five months of football after undergoing surgery on a ruptured pectoral muscle, the club has announced.

Keary incurred the injury against Penrith at the weekend's inaugural Dick Smith NRL Auckland Nines tournament and was rushed straight back to Sydney.

“We were able to get him back (to Sydney) straight after that game – he just got caught in an awkward position,” Rabbitohs High Performance Manager Troy Thomson said in a statement.

“He went in and got some surgery done yesterday (Monday) – which was our best case scenario and that repair was successful last night.

“He’s looking at a fairly long rehab program of about four or five months. So it’s unfortunate for Luke, but we’ll get our hands on him and get him back as quick as we can.”

The news is a blow to Souths, who had planned on moving last season's five-eighth John Sutton to the forward pack and partnering Keary with Adam Reynolds in the halves.

Coach Michael Maguire has the option of returning Sutton to pivot given his combination with Reynoldswas largely successful last year, but young gun Dylan Walker has also reportedly been used there during the pre season.

Walker played 16 games last year in the three quarter line, scoring eight tries, and was one of the stars of the recent Nines tournament where he was consistently one of the Rabbitohs' best on field.