The Kangaroos are into the semi-finals of the NAB Cup after defeating Fremantle 1.14.7 (100) to 0.13.13 (91) in an entertaining encounter at Telstra Dome on Sunday afternoon.The Roos led by 31 points midway through the third quarter, but had to see off a desperate late challenge from the Dockers to earn their semi-final berth against Carlton next week.Leigh Brown (17 disposals) was in fine form up forward for the Kangaroos, booting three goals, with their smaller players in Matt Cambpell (three goals) and Lindsay Thomas (two goals) also impressive.James Walker led Fremantle with 25 possession and he was well-supported by Josh Carr and Paul Hasleby who both had 24 touches.Nathan Thompson opened the scoring for the Roos with two goals inside a minute following strong marks inside 50, but the Dockers soon hit back as Paul Duffield capped a fine run with his first and Matthew Pavlich converting after outmarking Michael Firrito.Thompson had a hand in the Kangaroos' third as he created a turnover then found rookie Campbell who didn't disappoint. Fremantle had plenty of scoring chances as time ran down, but wayward kicking saw the visitors three points down at the first break.Former skipper Peter Bell erased that deficit with a superb running goal from an acute angle early in the second and then handed another to Ryan Murphy shortly after, but a bright 10-minute period from the Roos saw goals to livewire Thomas and Djaran Whyman.Duffield's second snapped the run and Hasleby had the Dockers back in front late in the see-sawing quarter. Shannon Grant had struggled to assert himself for much of the first half, but he made his presence felt in no uncertain terms when he stroked a nine-pointer home minutes before half-time.Justin Longmuir's goal shortly after made the Kangaroos' lead just two points at the long break, but that was quickly extended as they bounced out of the blocks when play resumed.The Roos threatened to run away with the game with the opening five goals of the third term. Recent first-round draft pick Lachlen Hansen booted the first two, Thomas added another, Campbell kept his wits about him to soccer one through when the ball came back at him off the goalpost and Brown put his side 31 points up when he slotted his second.The Dockers were able to regroup, however, and kept themselves in the contest with the final two goals of the quarter - including a brilliant snap from an almost impossible angle to Jeff Farmer - making the deficit 16 points at three-quarter time.The Kangaroos were in no mood to surrender the ascendancy in the final term, however, booting the first three goals to put themselves in the box seat for the win.A bit of spite crept into proceedings with a scuffle between Daniel Pratt and Farmer leading to a few spotfires breaking out around the ground, but this fired up the Dockers who came storming home with the last four goals of the match.Farmer booted the last two, but time ran out for the Dockers with the final siren sounding as they made one last desperate foray into their forward 50.KANGAROOS: 0.3.3, 1.6.5, 1.11.5, 1.14.7 (100)FREMANTLE: 0.2.6, 0.7.6, 0.9.10, 0.13.13 (91)NINE POINT GOALS: Kangaroos: GrantFremantle: NilSIX POINT GOALS: Kangaroos: Brown 3, Campbell 3, Hansen 2, Thomas 2, Thompson 2, Harvey, WhymanFremantle: Farmer 3, Duffield 2, Murphy 2, Bell, J Carr, Hasleby, Longmuir, Pavlich, BrowneBEST: Kangaroos: Brown, Sansbury, Simpson, Archer, Thomas, Campbell, GibsonFremantle: Hasleby, Walker, J Carr, Sandilands, Bell, Farmer, DuffieldINJURIES: Kangaroos: NilFremantle: NilREPORTS: NilCROWD: 9,191 at Telstra Dome