Newcastle fullback Shannon McDonnell will play Saturday's NRL match against South Sydney with his broken thumb in a splint.

McDonnell cracked a bone in the last tackle of Monday's last-gasp 34-30 loss to Penrith but has avoided surgery and is hopeful of playing on as the injury heals.

"It's all right, I'll get through the game all right, just strap it up and I'll try not to think about it," he told reporters on Thursday.

"I'll wear a splint in the game and it will be fine.

"I have a slight break in one of the bones but it's not too bad, I don't need surgery.

"It won't need a rest, I'll sort of play it out and it will heal itself."

McDonnell has been unable to train fully with the Knights this week but is confident of getting through an intense final session on Friday and avoiding a pain-killing injection for the Bluetongue Stadium clash with the Rabbitohs.

"(It was) just a light session today, not really worrying about catching the ball yet so I'll worry about that tomorrow and see how we go," he said.

Former Wests Tigers back McDonnell has replaced Kurt Gidley at fullback as the captain recovers from a serious hamstring injury.

The Knights have lost three straight games since their opening round upset of Canterbury.

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