Marshall, who had previously ruled himself out of the series to undergo surgery on a troublesome right shoulder, said he was yet to decide whether he'll participate in the games against Australia and Great Britain.
"At the moment I'm not worried about (the Tri-Nations), I'm just worried about this week," Marshall said at the Tigers' training session.
"That's in the future, but we'll see what happens later on.
"I haven't made my mind up."
Marshall said he had not been inconvenienced by the injury in recent weeks and had "100 per cent" confidence it would hold up to the rigours of semifinal football.
"It's not that bad," he said.
"It's feeling alright and I feel 100 per cent confident in my defence and the strength of my shoulder at the moment. I'm pretty happy with the way I'm doing."
The prospect of fielding a halves pairing of Marshall and Jones - who came out of international retirement to rejoin the New Zealand squad - was well received across the Tasman.
"That's fantastic," said Kiwis coach Brian McLennan.
"That's Benji's choice, anyone who plays for the Kiwis, it's their choice too.
"For Benji, all us Kiwis back home are just rooting for him and his Tigers mates.
"He's got plenty on his mind, the last thing I'll be doing is trying to get a hold of him now while he's in the semifinals.
"That's choice, mate."
McLennan's sentiments were echoed by New Zealand Rugby League (NZRL) boss Selwyn Pearson.
"That's wonderful news, if that's the case you've made an old man very happy," he said.
"It would be nice if he could do the southern leg of the Tri-Nations tour and then go under the knife."
However, Pearson was less enthused about the process used to rule NRL players out of the New Zealand side to undergo off-season surgery.
This is despite a decision by NRL chief executives to provide written medical reports and relevant information to the NZRL if a player is unable to take part in a test or tour.
The move was a response to claims by New Zealand officials that clubs had exaggerated injuries in an attempt to protect key personnel.
"We never disagree over the prognosis, we never disagree over the treatment required, it's always the rehab time that comes into conflict," Pearson said.
"The longer it is the less chance they have to tour and still have their operation and recover."
McLennan, who has already begun training the New Zealand-based players in preparation for the tests, said he was particularly impressed by Warriors giant Manu Vatuvei, whom he dubbed the next Jonah Lomu.
"Standing next to Manu Vatuvei and seeing the athleticism of him, he's going to be a superstar, this one," he said.
"For the size of him and how fast he is, he has real potential.
"I liken him to Jonah Lomu and he is, he's just so big and fast.
"TP (Tony Puletua) is a big man, well Manu is as big as TP but he can really fly, he's fast enough to be a fast winger or centre.
"He just needs to learn the ropes of the game."
"That's Sione's choice, but personally I think one day he will really regret that," McLennan said.Like