Man-of-the-Match Gilchrist struck nine boundaries in his 47-ball innings before he was caught at third man in the 16th over.
Fellow left-hander Matthew Hayden fell for 45 six overs later at 121 for two before Darren Lehmann and Damien Martyn shared an unbroken fourth-wicket stand of 50.
Australia had won the toss and sent Pakistan in to bat in the first game of the three-match series, restricting them to 176 for eight from 50 overs.
Pace bowler Andrew Bichel put Australia in control by taking three for 30, dismissing Inzamam-ul-Haq, Azhar Mahmood and Younis Khan in the 19th, 23rd and 25th overs as Pakistan slumped from 71 for two to 78 for five.
Wicket-keeper Gilchrist also took four catches and one stumping.
Pakistan opener Imran Nazir, who retired hurt for five in the fifth over after being struck on the forearm, returned to make a fighting 39 not out from 53 balls.
The only batsman to show any early resistance was Inzamam, who scored 33 off 42 balls to pass Australia’s Mark Waugh as the fourth highest run-scorer in one-day cricket.
Inzamam has scored 8,527 runs from 266 matches, bettering Waugh’s 8,500 from 244, but is still way short of Sachin Tendulkar’s record of 11,168 from 288 games.
The three-match series had been promoted as a clash for the title of world’s fastest bowler between Australia’s Brett Lee and Pakistan’s Shoaib Akhtar but both were missing Wednesday.
Lee was dropped and Shoaib was ruled out with a hip injury suffered during the pre-game warm-up.
Wednesday’s match, which attracted a crowd of 11,681, was played indoors with the retractable roof closed but the novelty of mid-winter international cricket had worn off for Melbourne’s sporting public.
The first match of the three-game series against South Africa in August 2000 attracted 25,785 at the same indoor venue.
PAKISTAN:
Imran Nazir not out 39
Shahid Afridi c Warne b McGrath 1
Yousuf Youhana c Gilchrist b Warne 19
Inzamam-ul-Haq c Gilchrist b Bichel 33
Younis Khan c Gilchrist b Bichel 16
Azhar Mahmood c Martyn b Bichel 1
Rashid Latif c Gilchrist b Lehmann 11
Shoaib Malik st Gilchrist b Lehmann 27
Wasim Akram c Hayden b Watson 13
Waqar Younis not out 9
EXTRAS (LB-2, W-4, NB-1) 7
TOTAL (for eight wkts, 50 overs) 176
FALL OF WKTS: 1-3, 2-55, 3-71, 4-75, 5-78, 6-104, 7-124, 8-153.
DID NOT BAT: Mohammad Sami.
BOWLING: McGrath 7-2-22-1; Gillespie 9-1-34-0 (1nb); Bichel 10-1-30-3 (1w); Warne 10-1-27-1; Watson 9-0-38-1 (2w); Lehmann 5-0-23-2 (1w).
AUSTRALIA:
A.C. Gilchrist c Shahid b Sami 56
M.L. Hayden c Shoaib b Sami 45
R.T. Ponting c Rashid b Shahid 13
D.R. Martyn not out 18
D.S. Lehmann not out 28
EXTRAS (LB-4, W-3, NB-10) 17
TOTAL (for three wkts, 32.5 overs) 177
FALL OF WKTS: 1-101, 2-121, 3-127.
DID NOT BAT: M.G. Bevan, S.R. Watson, S.K. Warne, A.J. Bichel, J.N. Gillespie, G.D. McGrath.
BOWLING: Wasim Akram 6-1-24-0 (1w); Waqar Younis 5-0-31-0 (1w); Mohammad Sami 9-0-53-2 (9nb, 2w); Shahid Afridi 5.5-0-20-1 (1nb); Shoaib Malik 2-0-16-0; Azhar Mahmood 5-0-29-0.
RESULT: Australia won by seven wickets.
UMPIRES: D.J. Harper (Australia) and R.B. Tiffin (Zimbabwe).
TV UMPIRE: S.J. Davis.
MATCH REFEREE: C.H. Lloyd (West Indies).
MAN-OF-THE-MATCH: Adam Gilchrist.
SECOND MATCH: Saturday, Melbourne
THIRD MATCH: Wednesday, Brisbane.—Reuters