Steve Jancetic AAP Penrith need a No.6, St George Illawarra a No.7 and Canberra have to fit three options into two spaces - welcome to the NRL's version of your morning sudoku. Seven NRL clubs joined already hard-at-work Penrith in returning to pre-season training on Monday. The remainder of their NRL rivals resume shortly and, while runs up sand hills and hours in the gym will no doubt be a feature, there's some sorting out to be done as well. Here's a look at what does each club needs to ponder this pre-season to boost their chances of success in 2013? BRISBANE How does Scott Prince fit into the Broncos picture? For so long the main main at both the Titans and Tigers, Prince wouldn't seem a likely candidate for a back-up role. What then for first-choice halves Peter Wallace and Corey Norman? Someone won't be happy. CANBERRA The Raiders need to get Josh Dugan's body right this off-season. They are a different side with him on the paddock, but he spends far too many games on the sidelines injured. The return of captain Terry Campese also creates a headache with who to leave out in the halves - Josh McCrone or Sam Williams. CANTERBURY Fitting ex-Manly star Tony Williams into a game plan which is already forward-dominated won't be too difficult. Halfback is still a problem for coach Des Hasler, with Kris Keating falling short of the mark in the 2012 grand final. CRONULLA Consecutive years of brilliant recruitment have the Sharks brimming with talent, but coach Shane Flanagan has a task bringing all his players together in the same game plan. Michael Gordon's stated desire to play fullback could be a problem if Nathan Gardner is fit. GOLD COAST Since their inception in 2007 the Titans have searched without success for someone to help ease the playmaking burden on halfback Scott Prince. Now with Prince shipped out, they have a hole at both No.6 and No.7, which must be coach John Cartwright's focus in coming months. MANLY Coach Geoff Toovey has to find some youth to take the burden off an ageing forward pack, with Tony Williams and young duo Daniel Harrison and Darcy Lussick having left the club. Toovey also needs to help five-eighth Kieran Foran rebound from a slightly disappointing campaign. MELBOURNE Having finally captured an NRL title to keep, how will coach Craig Bellamy keep his troops motivated next season? The return of Brett Finch adds depth around the halves, but Bellamy's main job will be mental rather than tactical this pre-season. NEWCASTLE Pre-season will all be about conditioning for a Knights squad that is starting to resemble Dad's Army, with veteran recruits Jeremy Smith, Beau Scott and David Fa'alogo joining the likes of old heads Danny Buderus, Willie Mason and Timana Tahu. NORTH QUEENSLAND The Cowboys' most important pre-season move may not come on the field or in the gym but in the office, with the re-signing of marquee man Johnathan Thurston a priority. And is Anthony Mitchell the fulltime answer to the vacant hooking role? PARRAMATTA What to do with a problem like Jarryd Hayne? Even if they snare Israel Folau, Hayne remains Parramatta's most dangerous player, but what position is his best? New coach Ricky Stuart last year said he didn't see Hayne as a fullback, but he has struggled when moved to five-eighth. PENRITH Who do the Panthers play at five-eighth? Lachlan Coote impressed when moved there midway though last year, but that would leave the fullback role open. What coach Ivan Cleary would give now to have been able to hold onto Michael Gordon. ST GEORGE ILLAWARRA The Dragons don't have a stand-out first choice for the halfback role, with an untested rookie (Josh Drinkwater), veteran utility (Nathan Fien) and an injury-prone playmaker (Kyle Stanley) all battling it out for the No.7 jumper. SOUTH SYDNEY After a brilliant rookie campaign, coach Michael Maguire will need to ensure halfback Adam Reynolds has enough support to ensure he doesn't suffer a dose of the second-year blues. SYDNEY ROOSTERS How do you prepare for a season in which the player who is likely to be central to your plans, Sonny Bill Williams, won't be there for nearly all the pre-season because of rugby union and boxing commitments? WARRIORS New coach Matthew Elliott wasn't the man the players wanted, so getting the players to buy into his plan will be a tough early task. Then he has to unlock the magic that went AWOL in 2012. WESTS TIGERS After claims key players wielded too much power at the Tigers, new coach Michael Potter first needs to establish that he is the boss. And with Benji Marshall having said he wants to return to the No.6 jumper, Potter may then have to work out what to do at halfback and with his two other five-eighth options, Braith Anasta and Curtis Sironen.