It was only 17-15 to The Western Stars after the first 10-minute quarter, but finally drew out to a comfortable 47-39 win at the final hooter.
Tournament organiser Julie Linklater said all three teams were from Whanganui and were regulars in the Monday and Tuesday night mixed netball tournament throughout the season.
"They pretty much all know each other, although that season finished in November last year, so they've not had much game time before the Masters," Linklater said.
"Every year we have the Monday-Tuesday night mixed evenings and then on a Wednesday night we have women only and it's extremely popular."
The outdoor women's serious and social age group competition begins at 9am on Friday and runs through until Sunday.