Fiji changes four forwards
All four changes come in the forwards with hooker Sunia Koto, lock Apisalome Ratuniyawara and No.8 Sakiusa Matadigo replaced by Tuapati Talemaitoga, Tevita Cavubati and Netani Talei respectively.
Flank Dominiko Waqaniburotu's place is taken by Clermont's Peceli Yato, after the former was found guilty of a tip tackle against England and suspended for one week.
McKee said the fact his team only had five days between matches was not a problem.
"We play with short turnarounds in the Pacific Nations Cup, so in terms of our systems, recovery and analysis, we have practised that," he said.
"We have made some changes to our forward pack which were pre-planned, to make sure we get a number of fresh players into the line-up but keeping the continuity with the core of our team."
Fiji fought bravely against England before going down 11-35 in their opening match, but could realistically have stayed more in touch had they bagged their kickable points with both flyhalf Ben Volavola and giant wing Nemani Nadolo missing kicks.
"We picked up some momentum in the second half and we got within seven," McKee added.
"The game was in the balance at that point and had we managed to have taken some points from our penalties, the final 20 minutes could have been quite different.
McKee admitted that the potential selection of Josh Matavesi at pivot had been "the main discussion point."
"In the end we have gone with the same backline combination. We believe by keeping the combination it will help us build on our performance against England," he stated.
Fiji's Pool A has been dubbed by many as the group of death, containing not only hosts England and two-time winners Australia, but also Wales.
"We have been well aware of the challenge ahead of us since the draw came out and we qualified," McKee said.
"Twickenham was a massive challenge for us take on [for the England match] with it being their home ground and doubling up as the opening game and ceremony. But our first game is behind us now and although we have another massive game coming up, we won't have those first game jitters.
"The boys are well aware of the pressures around the game, but I don't think those pressures will match the pressure of playing England at Twickenham in the opening game," McKee stated.
Australia named a very strong side to play Fiji, with a backrow featuring two proven flanks in Michael Hooper and David Pocock.
"We suspected Australia would go with Hooper and Pocock in the back row," acknowledged McKee.
"That was the combination that was so successful in the Bledisloe Cup game in Sydney just over a month ago, so they've gone with that again and it gives them good mobility in the back row."
McKee added that Japan's shock 34-32 victory over South Africa, widely regarded as world rugby's biggest ever upset, would inspire his team.
"It certainly will. It's great for the game and the boys were very happy for the Japanese team," the Kiwi coach said.
"It shows a number of things. It shows that the gap between tier one and tier two is closing. When you look back to previous World Cups, you can see how the scorelines are coming down.
"It shows what is being achieved. It also shows what can be achieved if you stick to a game plan and play to your strengths."
Fiji: 15 Metuisela Talebula, 14 Waisea Nayacalevu, 13 Vereniki Goneva, 12 Gabiriele Lovobalavu, 11 Nemani Nadolo, 10 Ben Volavola, 9 Nikola Matawalu, 8 Netani Talei, 7 Akapusi Qera (captain), 6 Peceli Yato, 5 Leone Nakarawa, 4 Tevita Cavubati, 3 Manasa Saulo, 2 Tuapati Talemaitoga, 1 Campese Ma'afu.
Replacements: 16 Viliame Veikoso, 17 Peni Ravai, 18 Isei Colati, 19 Nemia Soqeta, 20 Malakai Ravulo, 21 Nemia Kenatale, 22 Joshua Matavesi, 23 Aseli Tikoirotuma.
Date: Wednesday, September 23
Venue: Millennium Stadium, Cardiff
Kick-off: 16.45 (15.45 GMT; Thursday September 24 01.45 AEST; Thursday 24 September 03.45 FJT)
Referee: Chris Pollock (New Zealand)
Assistant referees: Nigel Owens (Wales), Leighton Hodges (Wales)
TMO: Graham Hughes (England)