Premiers North Queensland have been hit hard by injuries a month out from the NRL finals.
Hooker Jake Granville has been sidelined for two weeks due to a broken hand, while prop Ben Hannant will undergo knee surgery and is expected to be out for up to a month.
RayThompson will replace Granville at dummy-half for Sunday's round-23 clash with Sydney Roosters at Allianz Stadium, the Cowboys announced on Tuesday.
Patrick Kaufusi, who has signed a new one-year deal with the Cowboys, has replaced Hannant on the Cowboys' bench.
The Cowboys have slipped out of the top four after Sunday's loss to Wests Tigers at Leichhardt Oval. Superstar playmaker Johnathan Thurston returned from a week out with a hamstring injury against the Tigers, but was well below his best.
With Kyle Feldt available for selection for the clash with the Roosters after serving a three-match ban for a shoulder charge, North Queensland - who had had a good run with injuries until Thurston went down three weeks ago against Canterbury - were hoping to have their grand final winning 17 on the park this weekend.
However Cowboys coach Paul Green said that might not happen until week one of the finals series.
"It is not a major injury," Green told reporters in Townsville on Tuesday of Hannant's prospects.
"It is a torn meniscus and we won't fully know until they go in there (for surgery).
"But the initial diagnosis is three to four weeks."
Javid Bowen has been dumped from the wing to make way for Feldt.
"It is tough for Javid," Green said.
"Feldty has worked hard and he is pretty contrite about what he did. He feels like he wants to make up for it and this is his opportunity."
