"He doesn't have a lot of weaknesses, he's a really composed guy, on and off the field, has a terrific kicking game and really smart in regards to the way he goes about his footy.
"He doesn't mind going all the way into the line, so he's brave as well.''
Seibold's own halfback, Adam Reynolds, is tough and bound to cause the Roosters plenty of headaches as he returns to full fitness after surviving his comeback game against St George Illawarra last Friday.
"He put his hand up a couple of weeks ago to play, but I thought he was still a bit underdone,'' Seibold said. "He's had a good week at training and will get better.
"Our effort has been where we want it, we just need to build pressure on opposition teams, rather than put pressure on ourselves.''
You're in: Jason Clark (left) and Adam Reynolds at Souths training.
Photo: AAP
Murray was seen clutching his hamstring at Redfern on Tuesday and Seibold confirmed he had pulled up stiff.
"Jason Clark will start, it's his 150th game,"Seibold said. "He's an outstanding clubman, he gave us plenty of energy off the bench last week and it's a good opportunity for Clarky tomorrow night.
"Cam will be OK for next week, but he's pulled up sore and we won't take any risks with him.''
Clark, who has already been informed this will be his final season at his junior club, recalled his debut in 2009 and his first tackle on Wendell Sailor.
"I was lucky he tripped over me and I was lucky enough to hold on,'' Clark said.
"I'm happy to do my job for the club, it might not look fancy, but the boys around me know I'm doing my job, so that keeps me happy.''
