The highly experienced McCullough, who has played 260 NRL games for Brisbane over the past 11 seasons and three Origin games for Queensland, linked with the Knights last Thursday after negotiating a release from the Broncos.

His signing came after the Knights lost first string hooker Jayden Brailey for the season following a knee reconstruction.

McCullough trained strongly for his new club for the first time on Monday after arriving in Newcastle on Saturday night with O'Brien indicating over the weekend he would be thinking long and hard about whether to rush him straight in for the Panthers clash at Campbelltown Stadium.

While McCullough seems certain to be named in an extended squad, the Newcastle Herald understands O'Brien will likely opt to give the 30-year-old at least another week to settle in at the club before considering him for selection.

It also means he can reward Randall 24, one of the club's best trainers, who has shown enormous improvement over the summer, with his first game in the top grade.

The Lakes United junior is expected to share the hooking duties with ultility Connor Watson, who will also be used in a middle forward role against the Panthers.

Teenage centre Bradman Best, who is back fully fit from foot surgery after missing the opening two rounds, will be back in the side at left centre with Gehamat Shibasaki, Tautau Moga and Enari Tuala all vying for the right centre spot.

The Knights squad will be officially released at 4 pm.

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