1. Jared Waerea-Hargreaves (New Zealand)
The Kiwi prop packs an even bigger punch these days, having piled on 18kg this season. He first emerged as a relatively lean frontrower but now tips the scales around the 120kg mark after deciding lean wasn't mean enough. A famously fiery approach makes him a marked man, although the Roosters wrecking ball prefers to describe it as tackling technique issues. He was rubbed out for two illegal shots during the NRL this year and there was another marginal incident which left Newcastle legend Danny Buderis in Disneyland. If there were odds for the man most likely to have a serious World Cup stoush, Waerea- Hargreaves would be the favourite.
2. Sam Burgess (England)
The Burgess reputation grew in opposite ways during this year's NRL. The giant forward, England's talisman, cemented his position as one of the finest in the game yet a less savoury side also emerged. He was banned for putting the so-called "squirrel grip" on one opponent, and there were other incidents including lashing out with the foot and eye scraping.
No player will carry a bigger target. With so many English hopes riding on Burgess, how will he react especially if the host nation's disastrous pre-tournament form against Italy carries on? The 2013 NRL season created some mystery over the real Sam Burgess - the World Cup could reveal all.
3. Paul Gallen (Australia)
Gallen didn't need his hardman reputation enhancing - anyone who has watched the Cronulla brick in action knows he is as tough as it gets. Beating All Black Hika Elliot - a karate exponent - in the charity boxing ring did boost his street cred, however. Gallen is a forward who can go the distance which means even more time for trouble. He was once slated for trying to rip the stitches out of an opponent's head and his career is studded with bad press on and off the field. This year, he put the fight into the State of Origin with a flurry of blows to Nate Myles' head, sparking an old fashioned SoO war. Gallen is the Australian vice- captain but that is unlikely to hold him back.
4. Brett White (Ireland)
The ex-Australian and New South Wales prop doesn't have a huge charge sheet. But an unflattering reputation emerged because his infamous moments were decisively brutal and left such a mark on the recipients. He floored the great Queensland prop Steve Price with a hook and did the same to Cronulla's Ben Ross while playing for Melbourne. The State of Origin shocker led to Queensland deliberately putting up a bomb that enabled them to chase retaliation. In another incident, the Eels fumed over White's alleged chicken wing tackle that left Kiwi Nathan Cayless with a serious injury. White is more than capable of popping up in the bad books again.
5. Nate Myles (Australia)
If the Queensland stalwart gets his chance, watch out. The higher the level, the deeper Myles digs into his bag of dirty tricks - that's the way Steve "Blocker" Roach explains it. The legendary Roach was no angel himself. But after the Myles-Gallen Sate of Origin warfare this year, NSW assistant coach Roach let fly. The Blues blasted Myles for leading with his head and Roach detailed a list of crimes including ankle and knee twisting, plus the head-first cannonball into defenceless blokes. Roach reckoned Myles was a nice guy who pulled out the cheap shots in the State of Origin because he knew he would get away with it. World Cup refs be warned.