Ken Hinkley puts Port Adelaide's finals destiny on the shoulders of one ruckman Battle-scarred Power ruckman Matthew Lobbe leaves the field against Collingwood earlier in the season. MATTHEW Lobbe will go solo as Port Adelaide's lone dedicated ruckman against Collingwood in Saturday night's AFL preliminary final at the MCG. Power coach Ken Hinkley last night left a difficult selection meeting with the three changes that seemed inevitable. He has regained midfielder Hamish Hartlett (dislocated left shoulder and two-game suspension), midfielder-forward Robbie Gray (quad) and key defender Alipate Carlile (back). Hinkley has cast aside Hawthorn premiership ruckman Brent Renouf and cut two raw defenders - West Coast recruit Lewis Stevenson and Greater Western Sydney trade gain Jack Hombsch. He has preferred to retain the run of 18-year-old defender-midfielder Sam Colquhoun. The Central District draftee becomes the first 18-year-old to play an AFL final since Brownlow Medallist Chris Judd experienced September action at 18 in 2002. COLLINGWOOD resisted boosting its ruck battery to keep the inexperienced Brodie Grundy with West Coast recruit Quinten Lynch as his back-up. Magpies coach Nathan Buckley last night made two changes to gain the experience of 2010 premiership players, midfielder Luke Ball (calf) and defender Harry O'Brien (flu). They replace former Carlton defender Jordan Russell and Glenelg draftee Ben Kennedy. Port has a 7-4 win-loss this season when Lobbe has worked as a solo ruckman with key defender Jackson Trengove and key forward Justin Westhoff as back-up. The Power has the same 7-4 record when Lobbe has worked with a dedicated ruckman as his partner - 2-1 with the injured Jarrad Redden and 5-3 with Renouf. Until Hinkley recalled Renouf for Saturday's AAMI Stadium finale against Carlton - to ease the workload on Lobbe - the 24-year-old Victorian had more than proven he can handle big assignments on his own. Trengove described Lobbe as "super important" to the Power's improvement this season. The way he has carried our side as the No. 1 ruckman - doing 95-96 per cent of game time - has been a huge effort," said Trengove. We're really confident that he can carry us through this final series. He can carry us through a whole game. Trengove and swingman Westhoff this week continued their ruck training in anticipation of Hinkley reverting to the one-ruck model that gives the Power more run on the MCG. "Collingwood have a really good ruckman in Brodie Grundy, they could have brought back (premiership ruckman) Darren Jolly - and they have some primary big targets in attack," said Trengove. He expects the Magpies to keep Ben Reid in their forward zone with Travis Cloke rather than move Reid to defence. So Ken had to decide, do we play two ruckmen or go for run on the big ground of the MCG. That's another tough decision he had at selection. Port will train at Alberton today before travelling to Melbourne for its first final since the disastrous 2007 grand final campaign. Backs: Seedsman 40, Brown 16, Shaw 39 Half-backs: Williams 46, Keeffe 23, Goldsack 6 Centre: O'Brien 8, D. Beams 17, Didak 4 Half-forwards: Sidebottom 22, Lynch 21, Blair 11 Forwards: Ball 12, Cloke 32, Reid 20 Ruck: Grundy 35, Pendlebury 10, Swan 36 Interchange: Macaffer 3, Maxwell 5, Thomas 24, Dwyer 41. In: Ball, O'Brien Out: Russell, Kennedy. Backs: O'Shea 13, Carlile 27, Logan 44 Half-backs: Broadbent 5, Trengove 12, Jonas 42 Centre: Ebert 7, Boak 1, Cornes 18 Half-forwards: Gray 9, Westhoff 39, Cassisi 25 Forwards: Wingard 20, Schulz 28, Monfries 6 Ruck: Lobbe 23, Hartlett 8, Wines 16 Interchange: Moore 26, Pittard 29, Colquhoun 30, Young 40 In: Carlile, Gray, Hartlett Out: Renouf, Stevenson, Hombsch.