Despite being named to start at lock, Parramatta Eels' forward Ryan Matterson is in doubt to face the South Sydney Rabbitohs this weekend following a minor rib injury sustained in Round 15.

The newly minted Origin forward is struggling with a rib cartilage issue suffered in the club's 26-16 victory over the Sydney Roosters, with pain management the main factor over whether he is to take the field or not this weekend.

The injury caps off a rollercoaster month for Matterson, who made his Origin debut shortly before spurning the Dolphins to re-sign long-term with the Eels, before being dropped from the Blues side around the same time he suffered the rib injury.

Losing Matterson would be a massive loss for the Parramatta engine room, with the middle forward averaging 160 metres and over two offloads a game.

His scratching would likely see Isaiah Papali'i move into the middle, promoting Marata Niukore into the starting side, and either Bryce Cartwright or Nathan Brown would join the bench.

The task at hand is tough enough for Parramatta as it stands, already facing off against a returning Latrell Mitchell, desperate to prove he's ready to be thrown into the Origin arena after a two-month spell on the sidelines.

Head coach Brad Arthur will make a final call on Matterson later in the week, with Friday night's squad trim from 22 to 19 the likely indicator over his availability.

The Eels will be looking to snap a four-game losing streak to South Sydney, with the Rabbitohs scoring 38 points or more in each of those contests, a feat they could really use Matterson on board for.