Arnold is spoiled for choice leading into the Bluetongue Stadium clash with the likes of vice-captain John Hutchinson and Rostyn Griffiths vying for the same position.
The Mariners boss revealed that he would look over things today and tomorrow before making his final decision on the starting eleven and four substitutes.
“That's a close call," Arnold said this week.
"Hutch has come in and done a great job, he's an experienced player, but he's developed this season.
"Rostyn was great before he picked up three silly yellow cards which gave Hutch a chance in the starting side.
"It's a good position to be in, I won't decide until late who will play."
Another player whose position is not secure is leading scorer Matt Simon who has missed the past two matches with a knee injury. Arnold said he will not be risked if he is not fully fit.
“We won't take anyone into this game who is not 100 per cent fit,'' he added.
"Matty is a very important player for us but we need everyone at their best against a side like Brisbane.
"We'll wait and see how he pulls up.”