They now sit perilously in ninth spot level on 22 points with the seventh-ranked Dragons and eighth-placed Bulldogs and are looking to win at least four of their last five games to secure a finals spot.
"The energy was there against Cronulla but we need to be better defensively, in our execution and our effort," said McFadden.
"With the changes we had we were disjointed last week, which wasn't unexpected, but we're going to need big improvements in what is a huge game for us.
"We enjoy being able to play in Wellington and we've loved the way the people from around the region have supported us the last two times we've been down there."
The Warriors go into their 23rd clash against the joint-venture club boasting just four wins, three of which were achieved at Mt Smart Stadium.
Its eight years since they last beat them (44-16 in Auckland in 2007); the only survivors from the victory are Mannering - who scored two tries in the centres - and wing Manu Vatuvei.
Vatuvei went try-less last week but made a game-high 195 metres from 14 runs in his first match in more than a month. He remains four tries short of 150 career tries.
In their two previous home games at Westpac Stadium the Warriors lost 16-24 to Canterbury in 2013 before dispatching Wests Tigers 42-18 last year.
Front-rower Charlie Gubb has been named to play an NRL match in his hometown for the first time and will again start from the interchange bench after a powerful showing last week.
The 25-year-old is a product of the University Hunters club in the Capital, and will appear in just his sixth game this season and the 12th of an NRL career which started in 2013.
The Dragons are yet to confirm their side but will be without Kiwis test winger Jason Nightingale, who has been ruled out with a syndesmosis sprain in his right leg.
The 28-year-old suffered the injury during the Dragons 46-24 win over the Newcastle Knights at Jubilee Oval on Sunday.
Nightingale will be further assessed over the coming days to determine the extent of the injury but he is expected to be sidelined for at least a couple of weeks.
"Jason has undertaken an MRI scan and the results support the initial diagnosis of an ankle syndesmosis sprain sustained during the win over the Knights on Sunday," said Dragons High Performance Manager Mark Andrews.
Warriors: 1. Sam Tomkins, 2. Ken Maumalo, 3. Jonathan Wright, 4. Solomone Kata, 5. Manu Vatuvei, 6. Chad Townsend, 7. Tuimoala Lolohea, 8. Jacob Lillyman, 9. Nathan Friend, 10. Albert Vete, 11. Ben Matulino, 12. Simon Mannering, 13. Sebastine Ikahihifo.
Interchange: 14. Siliva Havili, 15. Sam Lisone, 16. Charlie Gubb, 17. Raymond Faitala-Mariner, 18. Dominique Peyroux.
