Rugby union covert Timana Tahu says Wests Tigers star Benji Marshall should forget about Japan and join a Super 14 franchise if he is serious about switching codes.

Tahu, who quit the NRL in 2007 to link with the NSW Waratahs, said Marshall would find the switch of codes difficult to manage if he didn't make it a fulltime change.

Marshall is currently exploring the possibility of playing for a Japanese rugby club during the next NRL off-season before returning to the Tigers in time for the 2010 NRL campaign.

Tahu said a move to Japan would be a soft option.

"He needs to come over here and play over here if he's going to try and crack it," Tahu told Fox Sports News on Wednesday.

"Japan, it's probably easier on the body, there's not as many good players over there, it's really a retirement package for a lot of players.

"If you're going to try and succeed in rugby, do it the right way and play in the Super 14 or for the ARU."

Tahu struggled to impose himself during his first year in the 15-man game, particularly with his ability to read the play in defence, though he did become a dual international when he represented the Wallabies during last year's Tri-Nations tournament.

The 28-year-old said Marshall could find success hard to come by in rugby union, where some of his individual brilliance would be nullified.

"Benji's really good for the Wests Tigers but rugby union's a team sport," Tahu said.

"You really need the whole team with you, it's a structured sport.

"I think he'll find it a lot harder.

"I think if you come into rugby thinking mentally as a rugby league player, you'll go nowhere."

NRL boss David Gallop poured cold water on Marshall's code-share plan, saying the Kiwi international had to choose one or the other.

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