Ba made a perfect start, with striker John Orobulu breaking the deadlock just 26 seconds into the match.
The Men in Black continued to control the match with quick passing, skilful play and relentless pressure on the Nadi defence.
Their dominance paid off again in the 23rd minute when Ba doubled their lead.
Etonia Dogalau then added a third goal before halftime, giving Ba a comfortable 3-0 advantage at the break.
Nadi came out with greater determination in the second half, with the young side showing confidence and producing some good attacking passages.
They created opportunities and looked more threatening going forward, but Ba's defence remained organised and disciplined.
The Nadi attack could not find a way through as Ba held firm and protected their three-goal advantage until the final whistle.
The result sees Ba become the final team to qualify for the semi-finals where they will face Extra Supermarket Labasa FC.
Ba coach Ravinesh Kumar says the message to his players before the match was simple, which was to win the game and secure their place in the semi-finals.
Kumar says the players followed the game plan and delivered the result.
He says Labasa will provide a tough challenge, with matches between the two sides always producing hard-fought contests.
Kumar says the team will now return to training and work on their strategies ahead of the semi-final.
He expects the Ba-Labasa clash to be a cracker and is calling on Ba supporters to turn out in numbers and get behind the team.
For Nadi, the defeat brings their campaign to an end, despite a spirited second-half effort.
In other matches, Labasa booked their place in the semi-finals after defeating Nasinu FC 2-1, while Vantex Solutions Navua FC secured their semi-final spot after playing to a nil-all draw against Khelvin Realtors Lautoka FC.
Meanwhile, the final pool match between Kells Investment/Global Care Suva FC and defending champions Stratum/Lincoln Rewa FC is currently underway.
The FMF IDC semi-finals will be played on Saturday, with the final scheduled for Sunday.
