The Baby Black Pearls prevailed 42-37 and Coach John Glassie said, with five countries vying for three spots in Botswana next year, it sets them up well for the rest of the tournament.
"They're older and a little bit more mature so we knew we were going in for a tough game. If we win two out of the next three games that potentially puts us in the top two, which is where we want to finish - that automatic qualifier," he said.
"Playing off for that third position is going to be a tough game - there's a lot of pressure on that - so if we can get through to playing off for the first position that is certainly a goal that we have in mind.
"PNG we know they're very athletic and play with a lot of passion so we're gearing up for another good game (on Tuesday). We watched them have a good game against Tonga and have a convincing win so we know definitely they're going to come out ready to play."
Fiji also started strongly, beating Tonga by 55-34 goals and Samoa by 47-33, while Papua New Guinea thrashed Tonga 65-33.
Tonga coach Nita Tauhalaliku said playing international tournaments has been an all-new experience for her squad.
"The girls seemed a bit nervous and not playing their 100 percent but the first quarter of the second they came back and they gave Fiji a little bit of pressure and they did good on their defence but they didn't hold on a bit longer and our shooting we didn't put in as much as we got chances," she said.
"Most of them are quite new and the first time out of the country as well and our team are all local players and they experienced not only that they are short and all the (other) teams are tall but I think we need to speed up and be more careful on our passing when we have it."
Samoa and Tonga clash on Tuesday afternoon followed by Papua New Guinea vs Cook Islands.
Nita Tauhalaliku said her players need to show more belief in themselves.
"At first we will try to get our game on from quarter one all the way to quarter four. We will work on our shooting to put in every ball that we have instead of missing more goals and our driving to the ball, we need to come forward to receive it instead of waiting for it and the taller defenders take it away from them," she said.
"We watched Samoa...the team are very strong but I think if we work on what we plan to work on tomorrow against Samoa I think we will be all right."
All teams will play each other once in a round robin format before playoffs first and third place, with the fifth ranked team playing against a local selection side.