Australia, batting first, were dismissed for 307 in 49 overs and Pakistan were bowled out for 266 in 45.4 overs.
David Warner scored his first century since returning from his ban as holders Australia ran out comfortable 41-run winners over Pakistan in the World Cup at Taunton on Wednesday.
The opener, back after serving a 12-month suspension for his part in last year's ball-tampering scandal, struck 107 in Australia's 307 all out in 49 overs.
Mohammad Amir took five wickets as Pakistan recovered from a poor start to limit Australia's total, and they were well in contention as they reached 136-2 in reply.
When Imam-ul-Haq was caught down the leg side off a wide delivery having just reached his half-century and Mohammad Hafeez fell just short of his when he hit a Finch full toss straight to deep square leg, Pakistan's chances faded.
But a thrilling counter-attack started by Hasan Ali and continued by skipper Sarfaraz Ahmed and Wahab Riaz put them right back in contention at 264-7 with six overs left.
Mitchell Starc settled Australian nerves when he had Riaz caught behind for 45 and two balls later bowled Amir before Sarfaraz was run out for 40 as Pakistan were dismissed for 266.