The Steamers sit in fifth in the Championship, on 13 points, six behind North Harbour in fourth, and can still make the playoffs.
''We haven't worked out how we are still in the running to be perfectly honest,'' said McMillan.
''We probably don't deserve to be in that position, but we were competitive in a number of games earlier on in the season and the accumulation of those bonus points have kept us in the hunt.
"We know that we've played well in patches in the last six or seven weeks and are confident in the ability of our team, but we need to show a lot more desperation and a lot more desire to get a result, not just for ourselves, but for our supporters and stakeholders. We owe it to a lot of people to stay in the hunt by getting a victory."
McMillan knows a bonus point victory from Sunday's game will put pressure on the teams above.
''But we've got to focus on winning first and foremost, and if the opportunity presents itself, to go for a bonus.''
The details
Bay of Plenty v Manawatu: Sunday October 9, 4.35pm
Rotorua International Stadium, Rotorua
Played: 29 (1951-2014) Manawatu wins: 10, Bay of Plenty wins: 17, Draws: 2
Last match: Bay of Plenty 29 Manawatu 27, September 3, 2014 in Palmerston North.
Last Manawatu win: Manawatu 30 Bay of Plenty 18, August 18, 2007 in Palmerston North.