Gatland is in his last campaign after 11 years as Wales head coach and is determined to end with a bang in Japan after starting Pool D with back-to-back wins against Georgia and Australia.
Next up for his team are McKee’s Fiji and what will be a New Zealand coaching reunion.
“I first came across Warren when we were coaching overseas. He was coaching Ireland and I was at Clermont,” McKee said. “I then went to coach at Connacht and he left Ireland to coach Wasps.
“Our relationship goes back a long way. He has had an incredible tenure in Wales and you can see the consistency he has brought to the Welsh team.
“They got to No.1 in the world rankings which is an outstanding effort. He will want to leave Wales on a high. We wish him all the best, but hopefully we can upset his party in Oita.”
Fiji ran Australia close in the first half of their first game before suffering a seismic shock and defeat by minnows Uruguay. They did bounce back with a win over Georgia last time out.
Against Georgia Fiji showed just how dangerous they can be and they posses some of the most threatening runners in the world game. Wales will have to be wary of them.
Leone Nakarawa, Viliame Mata, Semi Radradra and Josua Tuisova are all players who can cause opposition havoc if they get the ball in time and space.
Edinburgh loose forward Mata, who was named European and Guinness PRO14 player of the year last season, and who starts at eight on Wednesday, said: “For the Wales game we are training as if it is a final. The boys are going to give it their all knowing that it’s going to be a big game against Wales.
“They are going to be trying to top the pool, so they are going to be coming out with a big game. “They have some world class players and some I have seen playing in the PRO14, so I know they will bring a big game on Wednesday.”
McKee added: “Wales will certainly want to finish top of the pool and will want to avoid England in the quarter-finals, but all those things are irrelevant to us.
“What we have to do is to build on the momentum we have from the Georgia game. While Wales will be a different opponent it is a game we can do well in.
“We know Wales are a good side. They are coming off the Six Nations as champions and from what we have seen of them during the World Cup they are playing a bit more of an expansive game.”
Fiji claimed a famous World Cup win over Wales in 2007, but they have lost to Gatland’s men at the last two global showpieces (including a 66-0 result in 2011).
“Wales are probably a little bit more dangerous in attack and we know what a good defensive side they are. We are going to have to work very hard to score points,” McKee said.
“To beat Wales we will have to be absolutely on top of our game.”
Fiji team to face Wales
1. Campese Ma’afu
2. Samuel Matavesi
3. Manasa Saulo
4. Tevita Cavubati
5. Leone Nakarawa
6. Dominiko Waqaniburotu (capt.)
7. Semi Kunatani
8. Viliame Mata
9. Frank Lomani
10. Ben Volavola
11. Semi Radradra
12. Lepani Botia
13. Waisea Nayacalevu
14. Josua Tuisova
15. Kini Murimurivalu
16. Mesulame Dolokoto
17. Eroni Mawi
18. Peni Ravai
19. Apisalome Ratuniyarawa
20. Peceli Yato
21. Nikola Matawalu
22. Jale Vatubua
23. Josh Matavesi