Australia overcame some spirited resistance from Canada to post a seven-wicket win in the Group A clash in Bangalore.
The associate nation caused some early panic for the defending champions when they raced to 82-1 inside 12 overs, opener Hiral Patel hitting five fours and three sixes to make 54 in a hurry.
They had at one stage reached 150-2 but suffered a middle-order collapse to be bowled out for 211 in 45.4 overs, Brett Lee taking four wickets.
Shane Watson (94) and Brad Haddin (88) then rode their luck in the opening overs before blossoming in an opening stand worth 183.
The duo both perished before reaching their hundreds and Australia also lost skipper Ricky Ponting for seven, before getting over the finishing line with 91 balls to spare, stretching their unbeaten World Cup run to 34 games.
Batting first after winning the toss, Canada made an excellent start in Bangalore reaching 77-1 after 10 overs, with Patel bringing up his half-century off just 37 balls, before falling to Watson four runs later.
The 19-year-old hit three sixes and five boundaries in his breezy innings and added 41 runs each with John Davison and Zubin Surkari.
Surkari and Ashish Bagai looked to carry on from there, but Australia were able to bring down the scoring rate to just over four as Canada reached 131-2 at the halfway mark.
Shaun Tait then triggered a collapse with his double strike that sent back Bagai (39 off 55) and Surkari (34 off 69) besides ending their 68-run stand.
Canada meandered to 200-8 in the 43rd over, but Lee's double strike ended the innings 11 runs later with 4.2 overs remaining.
In reply, Watson and Haddin saw off a hostile opening spell from the Canada bowlers to set Australia on course to overhaul the target.
The Aussie openers preferred caution over aggression, but opened up after opting to take the batting powerplay and quickly took the champions to 100 in 22 overs and also raced to their individual half-centuries in quick succession.
Haddin took 63 balls to reach his half-century while Watson took eight more balls to reach the mark, but the duo switched gears thereafter hitting a flurry of sixes and boundaries to take Australia closer to victory.
Canada had a brief respite when Haddin was caught-behind off Davison for 88, but his mature innings studded with 11 boundaries and two sixes, had powered Australia to 183 in 29 overs.
Watson, who had hit just six boundaries to reach his half-century, smashed four sixes - including the biggest of the tournament at 104 meters - thereafter to move within six runs of a century.
But Harvir Baidwan denied him the glory by having him caught in the deep, leaving the remaining task to captain Ricky Ponting and his deputy Michael Clarke.
Ponting (7), however, departed with five runs needed for victory, but a boundary from new man Cameron White and a wide from Henry Osinde finished things off with over 15.1 overs remaining.