Asuma wrecks Zabuza.
A child Sakura could already notice Zabuza moving through the mist. Asuma is not only leagues above that Sakura, he is a close quarters specialist.
His knives will -EASILY- cut through Zabuza's sword, seeing as how Bee's swords did that just as easy.
1- Sakura only could see Zabuza moving on the mist when Zabuza was trapped by the haunt dogs and the mist started to dissapear
2- Kakashi with his sharingan could barely react to Zabuza's movements on the mist... Somebody without sensing skills or good reaction speed is in trouble here
3- Zabuza outsmarted Kakashi, and also speedblitzed him with his water prision jutsu, Zabuza can match Azuma in CQC
4- Water > Fire (Asuma's element)
5- Wind is useless against water
6- Asuma would be lost in the mist without sensing skills and also would be in trouble against zabuza's clones
Zabuza takes this mid-diff