Zabuza vs Beginning of Shippuden Naruto and Sakura
Round 1:
Zabuza from the Land of Waves arc vs Naruto and Sakura as they are during the bell test.
Knowledge: They all have knowledge from their previous encounters, plus Zabuza knows enough about Sakura's super strength to not try and tank a punch.
Location: Where Zabuza and Team 7 had their first fight.
Naruto can't use any of Kurama's chakra.
Round 2:
If you think the team takes the first round, Haku from the Land of Waves arc helps Zabuza out
Round 3: Haku helps Zabuza but Naruto can access the same amount of Kurama's chakra as he did against Haku in part 1