Electing to bat, the world champions scored 240 for six in fifty overs on a slow wicket after the West Indian bowlers bowled a tight leash in the beginning.
Australia left out Brad Hogg and Mathew Hayden while West Indies made two changes, bringing in Ian Bradshaw and Jerome Taylor.
Martyn (52) and Symonds (52) put up a crucial 73-run partnership for the fourth wicket after Australia were at a precarious 80 for three in the 24th over with both the openers as well as skipper Ricky Ponting back in the hut.
Martyn began slowly and on a pitch where good feet movement was must to survive and score. With the new man Symonds scoring at almost run-a-ball, he was happy to just rotate the strikes.
After scoring his 35th ODI fifty, Matryn tried to smash Bradshaw out of the park but only managed to hole it out to Morton at long off. He hit five fours in his 77-ball knock.
Once the partnership was broken, Symonds too followed Martyn back to pavilion. The sturdy right-hander hit two fours and two mighty sixes for his 59-ball 52.
Symonds was allured to play in air by Sarwan and was caught at long leg boundary.
With two new men in Michael Clarke and Michael Hussey at crease, scoring quick in the end overs was never going to be easy. Ramnaresh Sarwan had another success when he removed Clarke for 23. Hussey and Bradd Haddin made some runs but such tight was West Indies bowling line and length that even till the last ball slogging was not possible.
Earlier, the Oz didn't get it going in the beginning and the West Indian bowlers gave anything but room to the batsmen to chance their arms.
Mathew Hayden was benched and Shane Watson again found himself promoted up the order. Both Simon Katich and Watson looked settled to see off the new ball than to score. Ian Bradshaw and Dwyane Smith took full advantage of a slow pitch and overcast conditions, putting extra premium on scoring.
Watson tried to break the shackles and hit Smith for two fours in the sixth over to pep up scoring. But he tried a little too hard and found himself on his way back after edging Bradshaw to the first slip for 18.
Skipper Ricky Ponting was tentative and could survive only 12 balls before falling lbw to Taylor in his first over. At 37 for 2, another top order collapse was imminent but Simon Katich and Martyn fighting tried raising a partnership. Katich was painfully slow in his scoring and consumed 66 balls for 25. He was sent back by Gayle after he added 43 runs for third wicket with Martyn.