The 22-year old failed to overcome a low-grade MCL injury suffered against Penrith last week and will not make the flight over to the nation’s capital.
Knights coach Nathan Brown revealed that Brown was targeting a return to the field next week.
“It’s a minor MCL,” Brown told the club website.
“They’re hopeful of him, reasonably confident for next week. It’s a short term one.”
Kurt Mann will take Watson’s place in the side, and Brown was confident in his ability to get the job done.
“Kurt’s actually spent some time there in the pre-season,” Brown said.
“It’s not really new to Kurt.
“He fits in there easily.”